Lymphopenia: Reduction in the number of lymphocytes.T-Lymphocytopenia, Idiopathic CD4-Positive: Reproducible depletion of CD4+ lymphocytes below 300 per cubic millimeter in the absence of HIV infection or other known causes of immunodeficiency. This is a rare, heterogeneous syndrome and does not appear to be caused by a transmissible agent.Carboprost: A nonsteroidal abortifacient agent that is effective in both the first and second trimesters of PREGNANCY.Lymphocyte Count: The number of LYMPHOCYTES per unit volume of BLOOD.Propylene Glycols: Derivatives of propylene glycol (1,2-propanediol). They are used as humectants and solvents in pharmaceutical preparations.Rats, Inbred BB: A strain of Rattus norvegicus which is a model for spontaneous insulin-dependent diabetes mellitus (DIABETES MELLITUS, INSULIN-DEPENDENT).Leukocytosis: A transient increase in the number of leukocytes in a body fluid.Leukocyte Count: The number of WHITE BLOOD CELLS per unit volume in venous BLOOD. A differential leukocyte count measures the relative numbers of the different types of white cells.Receptors, Lysosphingolipid: A subfamily of lysophospholipid receptors with specificity for LYSOSPHINGOLIPIDS such as sphingosine-1-phosphate and sphingosine phosphorylcholine.Interleukin-7: A cytokine produced by bone marrow stromal cells that promotes the growth of B-LYMPHOCYTE precursors and is co-mitogenic with INTERLEUKIN-2 for mature T-LYMPHOCYTE activation.Lymphocytes: White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each), or NATURAL KILLER CELLS.T-Lymphocytes: Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (T-LYMPHOCYTES, CYTOTOXIC) and helper T-lymphocytes (T-LYMPHOCYTES, HELPER-INDUCER). They are formed when lymphocytes circulate through the THYMUS GLAND and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.Severe Combined Immunodeficiency: Group of rare congenital disorders characterized by impairment of both humoral and cell-mediated immunity, leukopenia, and low or absent antibody levels. It is inherited as an X-linked or autosomal recessive defect. Mutations occurring in many different genes cause human Severe Combined Immunodeficiency (SCID).Sphingosine: An amino alcohol with a long unsaturated hydrocarbon chain. Sphingosine and its derivative sphinganine are the major bases of the sphingolipids in mammals. (Dorland, 28th ed)Immunologic Deficiency Syndromes: Syndromes in which there is a deficiency or defect in the mechanisms of immunity, either cellular or humoral.CD4-Positive T-Lymphocytes: A critical subpopulation of T-lymphocytes involved in the induction of most immunological functions. The HIV virus has selective tropism for the T4 cell which expresses the CD4 phenotypic marker, a receptor for HIV. In fact, the key element in the profound immunosuppression seen in HIV infection is the depletion of this subset of T-lymphocytes.Food Coloring Agents: Natural or synthetic dyes used as coloring agents in processed foods.Thymus Gland: A single, unpaired primary lymphoid organ situated in the MEDIASTINUM, extending superiorly into the neck to the lower edge of the THYROID GLAND and inferiorly to the fourth costal cartilage. It is necessary for normal development of immunologic function early in life. By puberty, it begins to involute and much of the tissue is replaced by fat.Opportunistic Infections: An infection caused by an organism which becomes pathogenic under certain conditions, e.g., during immunosuppression.Lymphocyte Subsets: A classification of lymphocytes based on structurally or functionally different populations of cells.Dacarbazine: An antineoplastic agent. It has significant activity against melanomas. (from Martindale, The Extra Pharmacopoeia, 31st ed, p564)T-Lymphocyte Subsets: A classification of T-lymphocytes, especially into helper/inducer, suppressor/effector, and cytotoxic subsets, based on structurally or functionally different populations of cells.Antineoplastic Agents, Alkylating: A class of drugs that differs from other alkylating agents used clinically in that they are monofunctional and thus unable to cross-link cellular macromolecules. Among their common properties are a requirement for metabolic activation to intermediates with antitumor efficacy and the presence in their chemical structures of N-methyl groups, that after metabolism, can covalently modify cellular DNA. The precise mechanisms by which each of these drugs acts to kill tumor cells are not completely understood. (From AMA, Drug Evaluations Annual, 1994, p2026)Blood Cell Count: The number of LEUKOCYTES and ERYTHROCYTES per unit volume in a sample of venous BLOOD. A complete blood count (CBC) also includes measurement of the HEMOGLOBIN; HEMATOCRIT; and ERYTHROCYTE INDICES.LeukopeniaImmunosuppressive Agents: Agents that suppress immune function by one of several mechanisms of action. Classical cytotoxic immunosuppressants act by inhibiting DNA synthesis. Others may act through activation of T-CELLS or by inhibiting the activation of HELPER CELLS. While immunosuppression has been brought about in the past primarily to prevent rejection of transplanted organs, new applications involving mediation of the effects of INTERLEUKINS and other CYTOKINES are emerging.Lymphopoiesis: Formation of LYMPHOCYTES and PLASMA CELLS from the lymphoid stem cells which develop from the pluripotent HEMATOPOIETIC STEM CELLS in the BONE MARROW. These lymphoid stem cells differentiate into T-LYMPHOCYTES; B-LYMPHOCYTES; PLASMA CELLS; or NK-cells (KILLER CELLS, NATURAL) depending on the organ or tissues (LYMPHOID TISSUE) to which they migrate.Spleen: An encapsulated lymphatic organ through which venous blood filters.Flow Cytometry: Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.Homeostasis: The processes whereby the internal environment of an organism tends to remain balanced and stable.Lupus Erythematosus, Systemic: A chronic, relapsing, inflammatory, and often febrile multisystemic disorder of connective tissue, characterized principally by involvement of the skin, joints, kidneys, and serosal membranes. It is of unknown etiology, but is thought to represent a failure of the regulatory mechanisms of the autoimmune system. The disease is marked by a wide range of system dysfunctions, an elevated erythrocyte sedimentation rate, and the formation of LE cells in the blood or bone marrow.Neutropenia: A decrease in the number of NEUTROPHILS found in the blood.B-Lymphocytes: Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation.Mice, Inbred C57BLT-Lymphocytes, Regulatory: CD4-positive T cells that inhibit immunopathology or autoimmune disease in vivo. They inhibit the immune response by influencing the activity of other cell types. Regulatory T-cells include naturally occurring CD4+CD25+ cells, IL-10 secreting Tr1 cells, and Th3 cells.Adoptive Transfer: Form of passive immunization where previously sensitized immunologic agents (cells or serum) are transferred to non-immune recipients. When transfer of cells is used as a therapy for the treatment of neoplasms, it is called adoptive immunotherapy (IMMUNOTHERAPY, ADOPTIVE).CD8-Positive T-Lymphocytes: A critical subpopulation of regulatory T-lymphocytes involved in MHC Class I-restricted interactions. They include both cytotoxic T-lymphocytes (T-LYMPHOCYTES, CYTOTOXIC) and CD8+ suppressor T-lymphocytes.Receptors, Interleukin-7: Cell surface receptors that are specific for INTERLEUKIN-7. They are present on T-LYMPHOCYTES and B-LYMPHOCYTE precursors. The receptors are heterodimeric proteins consisting of the INTERLEUKIN-5 RECEPTOR ALPHA SUBUNIT and the CYTOKINE RECEPTOR COMMON BETA SUBUNIT.Lymphocyte Activation: Morphologic alteration of small B LYMPHOCYTES or T LYMPHOCYTES in culture into large blast-like cells able to synthesize DNA and RNA and to divide mitotically. It is induced by INTERLEUKINS; MITOGENS such as PHYTOHEMAGGLUTININS, and by specific ANTIGENS. It may also occur in vivo as in GRAFT REJECTION.Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis: Group of systemic vasculitis with a strong association with ANCA. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls.Lymphocyte Depletion: Immunosuppression by reduction of circulating lymphocytes or by T-cell depletion of bone marrow. The former may be accomplished in vivo by thoracic duct drainage or administration of antilymphocyte serum. The latter is performed ex vivo on bone marrow before its transplantation.Cell Proliferation: All of the processes involved in increasing CELL NUMBER including CELL DIVISION.Immunocompromised Host: A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation.Lupus Vasculitis, Central Nervous System: Central nervous system vasculitis that is associated with SYSTEMIC LUPUS ERYTHEMATOSUS. Clinical manifestations may include DEMENTIA; SEIZURES; CRANIAL NERVE DISEASES; HEMIPARESIS; BLINDNESS; DYSPHASIA; and other neurological disorders.Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Autoimmunity: Process whereby the immune system reacts against the body's own tissues. Autoimmunity may produce or be caused by AUTOIMMUNE DISEASES.Lymphoid Tissue: Specialized tissues that are components of the lymphatic system. They provide fixed locations within the body where a variety of LYMPHOCYTES can form, mature and multiply. The lymphoid tissues are connected by a network of LYMPHATIC VESSELS.CD4-CD8 Ratio: Ratio of T-LYMPHOCYTES that express the CD4 ANTIGEN to those that express the CD8 ANTIGEN. This value is commonly assessed in the diagnosis and staging of diseases affecting the IMMUNE SYSTEM including HIV INFECTIONS.Rats, Inbred LewThymectomy: Surgical removal of the thymus gland. (Dorland, 28th ed)Bone Marrow: The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells.Antibodies, Neoplasm: Immunoglobulins induced by antigens specific for tumors other than the normally occurring HISTOCOMPATIBILITY ANTIGENS.
Dipropylene glycolLeukocytosisImmune receptor: An immune receptor (or immunologic receptor) is a receptor, usually on a cell membrane, which binds to a substance (for example, a cytokine) and causes a response in the immune system.Intraepithelial lymphocyte: Intraepithelial lymphocytes (IEL) are lymphocytes found in the epithelial layer of mammalian mucosal linings, such as the gastrointestinal (GI) tract and reproductive tract. However, unlike other T cells, IELs do not need priming.PMHC cellular microarray: PMHC cellular microarrays are a type of cellular microarray that has been spotted with pMHC complexes peptide-MHC class I or peptide-MHC class II.Reticular dysgenesisArthur Spiegel: Arthur Spiegel was the Chicago mail-order magnate and early American film studio executive.European Society for Primary Immunodeficiencies: The European Society for Primary Immunodeficiencies (ESID) is a Europe-wide medical association for healthcare professionals and researchers who deal with primary immunodeficiency diseases (PID).Caramel: Caramel ( or ) is a beige to dark-brown confectionery product made by heating a variety of sugars. It can be used as a flavoring in puddings and desserts, as a filling in bonbons, or as a topping for ice cream and custard.Hassall's corpuscles: Hassall's corpuscles (or thymic corpuscles (bodies)) are structures found in the medulla of the human thymus, formed from eosinophilic type VI epithelial reticular cells arranged concentrically. These concentric corpuscles are composed of a central mass, consisting of one or more granular cells, and of a capsule formed of epithelioid cells.DacarbazineBlood cell: A blood cell, also called a hemocyte, hematocyte, or hematopoietic cell, is a cell produced through hematopoiesis and is normally found in blood. In mammals, these fall into three general categories:Immunosuppressive drug: Immunosuppressive drugs or immunosuppressive agents or antirejection medications are drugs that inhibit or prevent activity of the immune system. They are used in immunosuppressive therapy to:Periarteriolar lymphoid sheaths: Periarteriolar lymphoid sheaths (or periarterial lymphatic sheaths, or PALS) are a portion of the white pulp of the spleen. They are populated largely by T cells and surround central arteries within the spleen; the PALS T-cells are presented with blood borne antigens via myeloid dendritic cells.Flow cytometry: In biotechnology, flow cytometry is a laser-based, biophysical technology employed in cell counting, cell sorting, biomarker detection and protein engineering, by suspending cells in a stream of fluid and passing them by an electronic detection apparatus. It allows simultaneous multiparametric analysis of the physical and chemical characteristics of up to thousands of particles per second.Systemic lupus erythematosus and pregnancy: For women with systemic lupus erythematosus (SLE), pregnancy can present some particular challenges for both mother and child.Cyclic neutropeniaPolyclonal B cell response: Polyclonal B cell response is a natural mode of immune response exhibited by the adaptive immune system of mammals. It ensures that a single antigen is recognized and attacked through its overlapping parts, called epitopes, by multiple clones of B cell.Suppressor-inducer T cell: Suppressor-inducer T cells are a specific subset of CD4+ T helper cells that "induce" CD8+ cytotoxic T cells to become "suppressor" cells. Suppressor T cells are also known as CD25+–Foxp3+ regulatory T cells (nTregs), and reduce inflammation.Protective autoimmunity: Protective autoimmunity is a condition in which cells of the adaptive immune system contribute to maintenance of the functional integrity of a tissue, or facilitate its repair following an insult. The term ‘protective autoimmunity’ was coined by Prof.ThymectomyBone marrow suppression: Bone marrow suppression or myelotoxicity (adjective myelotoxic) or myelosuppression is the decrease in production of cells responsible for providing immunity (leukocytes), carrying oxygen (erythrocytes), and/or those responsible for normal blood clotting (thrombocytes). Bone marrow suppression is a serious side effect of chemotherapy and certain drugs affecting the immune system such as azathioprine.
(1/980) Weekly administration of 2-chlorodeoxyadenosine in patients with hairy-cell leukemia is effective and reduces infectious complications.
BACKGROUND AND OBJECTIVE: It has been widely demonstrated that one single 7-day course continuous infusion (c.i.) 2-chlorodeoxyadenosine (2-CdA) at a dose of 0.1 mg/kg daily is dramatically effective in inducing high and prolonged complete remission (CR) rates in patients with hairy-cell leukemia (HCL). However, 2-CdA administration often results in severe neutropenia and lymphocytopenia both responsible for the infectious complications observed in these patients. We previously reported preliminary data regarding the effectiveness and toxicity of a modified protocol of 2-CdA administration (0.15 mg/kg 2 hours infusion once a week for 6 courses) in 25 HCL patients. This treatment schedule produced a similar overall response rate compared to standard 2-CdA regimen and appeared to be followed by a lower incidence of infectious episodes. In the present study we report response rate and toxicity of weekly 2CdA administration in a larger cohort of patients and with a longer follow-up. DESIGN AND METHODS: In a group of HCL patients with a pronounced decrease in neutrophils count (< 1 x 10(9)/L), we modified the standard protocol (0.1 mg/kg daily x 7 days c.i.) by administering 2-CdA at a dose of 0.15 mg/kg 2 hours infusion once a week for 6 courses. Thirty HCL patients, 24 males and 6 females with a median age of 56 years (range 37-76), entered into this protocol. Seventeen out of 30 patients were at diagnosis while the remaining 13 had been previously treated with alpha-interferon (alpha-IFN) (7), or 2-CdA (4) or deoxycoformycin (DCF) (2). RESULTS: Overall, 22/30 (73%) patients achieved CR and 8 (27%) partial remission (PR) with a median duration of response at the time of writing of 35 months, ranging from 6 to 58 months. Five patients (1 CR and 4 PR) have so far progressed. The treatment was very well tolerated. Five out of 30 patients (16%) developed severe neutropenia (neutrophils < 0.5 x 10(9)/L) and only in two of them we did register an infectious complication which required treatment with systemic antibiotics and granulocyte colony-stimulating factor (G-CSF). INTERPRETATION AND CONCLUSIONS: In conclusion, we confirm that weekly administration of 2-CdA at a dose of 0.15 mg/kg for 6 courses appears to be very effective in HCL inducing a high CR rate, similar to that observed with daily c.i. administration. CR durability and relapse/progression rates are also comparable to standard 2-CdA schedule. Moreover this new regimen seems to be safer in pancytopenic patients, markedly reducing life-threatening infectious complications. (+info)
(2/980) Does HIV cause depletion of CD4+ T cells in vivo by the induction of apoptosis?
The central pathogenic feature of AIDS is the dramatic loss of CD4+ lymphocytes. Despite more than a decade of intense research, the exact mechanism by which HIV causes this is still not understood. A major model for T cell depletion, proposed originally by Ameison and Capron in a report published in 1991, is that HIV sensitizes CD4+ T cells for activation-induced apoptosis. The apoptotic model of T cell depletion is discussed, and experiments that address the questions of whether apoptosis is restricted to infected cells or 'bystander' T cells, and whether T cell apoptosis requires participation of separate HIV-infected haematopoietic cell populations, are reviewed. (+info)
(3/980) CD4 depletion in HIV-infected haemophilia patients is associated with rapid clearance of immune complex-coated CD4+ lymphocytes.
The predominant immunological finding in HIV+ haemophilia patients is a decrease of CD4+ lymphocytes during progression of the disease. Depletion of CD4+ lymphocytes is paralleled by an increase in the proportion of immune complex-coated CD4+ cells. We examined the hypothesis that the formation of immune complexes on CD4+ lymphocytes is followed by rapid clearance of immune complex-coated CD4+ lymphocytes from the circulation. In this study, the relationship of relative to absolute numbers of immune complex-loaded CD4+ blood lymphocytes and their association with viral load were studied. Two measurements of relative and absolute numbers of gp120-, IgG- and/or IgM-loaded CD4+ lymphocytes were analysed in HIV+ and HIV- haemophilia patients, with a median interval of approx. 3 years. Immune complexes on CD4+ lymphocytes were determined using double-fluorescence flow cytometry and whole blood samples. Viral load was assessed using NASBA and Nuclisens kits. Whereas the proportion of immune complex-coated CD4+ lymphocytes increased with progression of the disease, absolute numbers of immune complex-coated CD4+ lymphocytes in the blood were consistently low. Relative increases of immune complex-coated CD4+ blood lymphocytes were significantly associated with decreases of absolute numbers of circulating CD4+ lymphocytes. The gp120 load on CD4+ blood lymphocytes increased in parallel with the viral load in the blood. These results indicate that immune complex-coated CD4+ lymphocytes are rapidly cleared from the circulation, suggesting that CD4+ reactive autoantibodies and immune complexes are relevant factors in the pathogenesis of AIDS. Relative increases of immune complex-positive cells seem to be a consequence of both an increasing retroviral activity as well as a stronger loading with immune complexes of the reduced number of CD4+ cells remaining during the process of CD4 depletion. The two mechanisms seem to enhance each other and contribute to the progressive CD4 decrease during the course of the disease. (+info)
(4/980) Anti-CD95 (APO-1/Fas) autoantibodies and T cell depletion in human immunodeficiency virus type 1 (HIV-1)-infected children.
Advanced stages of HIV-1-infection are characterized by progressive CD4+ T cell depletion. Peripheral T cells from HIV-1+ donors show accelerated apoptosis in vitro. The CD95 (APO-1/Fas) receptor/ligand system is involved in this process. To further study deregulation of the CD95 system in peripheral T cells during HIV-1-infection, we measured CD95-expression on CD4+ and CD8+ T cells together with serum levels of soluble CD95 (sCD95) and anti-CD95 autoantibodies in HIV-1+ children and healthy controls. Anti-CD95 levels in HIV-1+ children were significantly elevated when compared to uninfected controls, whereas serum levels of sCD95 were not different. In HIV-1+ children, CD95-expression on CD4+ and CD8+ T cells increased with age. A strong correlation between depletion of CD4+ cells in vivo and increase in CD95-expression on CD4+ T cells was observed. In contrast, such a correlation was not found for CD8+ T cells. A negative correlation between anti-CD95 autoantibody levels and CD4+ T cell counts, that was predicted by multiple linear regression analysis of pooled data, was found in individual patients observed longitudinally by repeated measurements. Since anti-CD95 autoantibodies isolated from HIV-infected adults have previously been shown to induce apoptosis of sensitive target cells in vitro, we speculate that the interaction of these antibodies with CD95-positive and CD95-sensitive T cells in vivo might be involved in progressive T cell loss during HIV-1-infection. (+info)
(5/980) The effects of extracorporeal whole body hyperthermia on the functional and phenotypic features of canine peripheral blood mononuclear cells (PBMC).
In this study the effect of transient 42.3 degrees C whole body hyperthermia (WBH) on the distribution of PBMC phenotypes and in vitro blastogenic responsiveness was determined in dogs. Hyperthermia (n = 6) was induced by heating venous blood during extracorporeal circulation (venous perfusion WBH); perfused non-heated dogs (n = 4) were used as controls. Both euthermic and hyperthermic perfusion produced transient lymphopenia which normalized in controls after perfusion but persisted in hyperthermic animals throughout the 8-day post-perfusion observation interval. The transient lymphopenia in control dogs was non-selective. In contrast, WBH-associated lymphopenia was selective, in that CD5+ T lymphocytes were more sensitive to hyperthermia than sIg+ B cells and, within the T cell compartment, suppressor (CD8+) cells were more sensitive to hyperthermic stress than helper (CD4+) lymphocytes. Functional analyses showed that WBH caused persistent suppression of PBMC blastogenesis in response to T cell phytomitogens. Increased plasma cortisol levels were correlated to peak lymphopenia and hyporesponsiveness to phytomitogens. Despite these alterations, high grade WBH was well tolerated and there was no evidence of opportunistic infection. (+info)
(6/980) Mice deficient in CD4 T cells have only transiently diminished levels of IFN-gamma, yet succumb to tuberculosis.
CD4 T cells are important in the protective immune response against tuberculosis. Two mouse models deficient in CD4 T cells were used to examine the mechanism by which these cells participate in protection against Mycobacterium tuberculosis challenge. Transgenic mice deficient in either MHC class II or CD4 molecules demonstrated increased susceptibility to M. tuberculosis, compared with wild-type mice. MHC class II-/- mice were more susceptible than CD4-/- mice, as measured by survival following M. tuberculosis challenge, but the relative resistance of CD4-/- mice did not appear to be due to increased numbers of CD4-8- (double-negative) T cells. Analysis of in vivo IFN-gamma production in the lungs of infected mice revealed that both mutant mouse strains were only transiently impaired in their ability to produce IFN-gamma following infection. At 2 wk postinfection, IFN-gamma production, assessed by RT-PCR and intracellular cytokine staining, in the mutant mice was reduced by >50% compared with that in wild-type mice. However, by 4 wk postinfection, both mutant and wild-type mice had similar levels of IFN-gamma mRNA and protein production. In CD4 T cell-deficient mice, IFN-gamma production was due to CD8 T cells. Thus, the importance of IFN-gamma production by CD4 T cells appears to be early in infection, lending support to the hypothesis that early events in M. tuberculosis infection are crucial determinants of the course of infection. (+info)
(7/980) Treatment of idiopathic CD4 T lymphocytopenia with IL-2.
Idiopathic CD4 T lymphocytopenia (ICL) is an unusual immune defect in which there is an unexplained deficit of CD4 T cells, leading to fungal, parasitic or other serious opportunistic infections. Current treatment efforts are directed at eliminating infections. Here we describe the use of a novel treatment, subcutaneous polyethylene glycol (PEG)-IL-2 injections, in a woman with this disorder, who had chronic severe mycobacterial disease which led to repeated hospitalizations, and advancing respiratory insufficiency. For this patient, PEG-IL-2, 50 000 U/m2, has been given by weekly subcutaneous injections for 5.5 years. This treatment has resulted in marked (and still continuing) long-term immunological improvement with normalized T cell functions and increased CD4 cell numbers. She has had substantial clinical improvement with clearing of mycobacterial disease, reducing hospitalizations and improved lung functions. The improvement seen in this patient suggests that low-dose IL-2 is a safe and practical therapy, which might be useful in other subjects with this potentially serious immune defect. (+info)
(8/980) Early arrest in B cell development in transgenic mice that express the E41K Bruton's tyrosine kinase mutant under the control of the CD19 promoter region.
Bruton's tyrosine kinase (Btk) is a nonreceptor protein kinase that is defective in X-linked agammaglobulinemia in humans and in X-linked immunodeficiency in mice. To study the effect of Btk activation in early B cell development in vivo, we have created transgenic mouse strains expressing Btk under the control of the human CD19 promoter region. The transgenic expression of wild-type human Btk corrected all X-linked immunodeficiency features in mice carrying a targeted disruption of the Btk gene. In contrast, expression of an activated form of Btk, the E41K mutant, resulted in an almost complete arrest of B cell development in the immature IgM+IgD- B cell stage in the bone marrow, irrespective of the presence of the endogenous intact Btk gene. Immature B cells were arrested at the progression from IgMlow into IgMhigh cells, which reflects the first immune tolerance checkpoint at which autoreactive B cells become susceptible to apoptosis. As the constitutive activation of Btk is likely to mimic B cell receptor occupancy by autoantigens in the bone marrow, our findings are consistent with a role for Btk as a mediator of B cell receptor-induced apoptotic signals in the immature B cell stage. Whereas the peripheral mature B cell pool was reduced to <1% of the normal size, significant numbers of IgM-secreting plasma cells were present in the spleen. Serum IgM levels were substantial and increased with age, but specific Ab responses in vivo were lacking. We conclude that the residual peripheral B cells were efficiently driven into IgM+ plasma cell differentiation, apparently without functional selection. (+info)