Immunodeficiency due to a unique protracted developmental delay in the B-cell lineage. (1/95)

A unique immune deficiency in a 24-month-old male characterized by a transient but protracted developmental delay in the B-cell lineage is reported. Significant deficiencies in the number of B cells in the blood, the concentrations of immunoglobulins in the serum, and the titers of antibodies to T-dependent and T-independent antigens resolved spontaneously by the age of 39 months in a sequence that duplicated the normal development of the B-cell lineage: blood B cells followed by immunoglobulin M (IgM), IgG, IgA, and specific IgG antibodies to T-independent antigens (pneumococcal polysaccharides). Because of the sequence of recovery, the disorder could have been confused with other defects in humoral immunity, depending on when in the course of disease immunologic studies were conducted. Investigations of X-chromosome polymorphisms suggested that the disorder was not X linked in that the mother appeared to have identical X chromosomes. An autosomal recessive disorder involving a gene that controls B-cell development and maturation seems more likely. In summary, this case appears to be a novel protracted delay in the development of the B-cell lineage, possibly due to an autosomal recessive genetic defect.  (+info)

The significance of IgG subclasses and mannan-binding lectin (MBL) for susceptibility to infection in apparently healthy adults with IgA deficiency. (2/95)

The aim of this study was to investigate the significance of IgG subclasses and MBL for susceptibility to infection in association with IgA deficiency. The study population consisted of 139 apparently healthy adult blood donors with IgA deficiency and normal serum levels of IgG and IgM, and an increased susceptibility to infection demonstrated at a population level. Additionally, 216 controls matched for age and sex were investigated. IgG4 deficiency was more common and the mean level of IgG4 lower in persons with IgA deficiency than in the controls. No significant associations could be demonstrated between overt IgG subclass deficiencies and increased susceptibility to infection. However, when the mean concentrations of IgG subclasses were analysed with regard to medical history, that of IgG1 was lower in persons who reported recurrent viral respiratory infections, that of IgG3 in persons who had episodes of severe infection in their history, and that of IgG4 in persons who had recurrent mild respiratory infections, compared with those who had no particular history of infections. In contrast, MBL deficiency-alone or combined with that of the IgG subclass-was not associated with increased susceptibility to infection in persons with IgA deficiency. The results indicate that the proneness to infections observed in a population of otherwise healthy persons with IgA deficiency can only for a small part be accounted for by concomitant deficiencies of IgG subclasses. Contrary to expectations, no synergism between the deficiencies of IgA and MBL could be demonstrated.  (+info)

Reduced IL-4-, lipopolysaccharide-, and IFN-gamma-induced MHC class II expression in mice lacking class II transactivator due to targeted deletion of the GTP-binding domain. (3/95)

Class II transactivator (CIITA) is an unusual transcriptional coactivator in that it contains a functionally important, GTP-binding consensus domain. To assess the functional role of the GTP-binding domain of CIITA in vivo, we have generated knockout mice that bear a mutation in the CIITA gene spanning the GTP-binding domain. Upon analysis, these mice show no detectable CIITA mRNA; hence, they represent mice with deleted CIITA rather than mice with defects in the GTP-binding domain only. In these knockout mice, MHC class II expression is nearly eliminated, although a faint RT-PCR signal is visible in spleen, lymph node, and thymus, suggestive of the presence of CIITA-independent regulation of MHC class II expression. Invariant chain expression is also greatly reduced, but to a lesser extent than MHC class II. Serum IgM is not decreased, but the serum IgG level is greatly reduced, further confirming the absence of MHC class II Ag-dependent Ig class switching. Induction of MHC class II expression by IL-4 or LPS was absent on B cells, and Mac-1+ cells showed no detectable induction of MHC class II by either IL-4, LPS, or IFN-gamma. These findings demonstrate a requirement for CIITA in IFN-gamma-, IL-4-, and endotoxin-induced MHC class II expression as well as the possibility of rare CIITA-independent MHC class II expression.  (+info)

Clinical and immunological evaluation of patients with mild IgG1 deficiency. (4/95)

Serum IgG subclass concentrations were determined in patients visiting, the pulmonology out-patient clinic with chronic respiratory tract problems. A total of 24 patients with a serum IgG1 concentration < 4.9 g/l (i.e. below the reference range) and normal values for IgG2, IgM and IgA were included. Patients with a selective IgG1 deficiency were vaccinated with a 23-valent pneumococcal polysaccharide vaccine. There were nine patients with a poor antibody response to pneumococcal capsular polysaccharide antigens. Responsiveness to protein antigens was intact in all patients. Patients with pneumonia showed a significantly lower anti-polysaccharide response in the IgG2 subclass than patients without pneumonia. Patients with recurrent sinusitis showed a significantly lower response in the IgA isotype after vaccination with pneumococcal polysaccharide vaccine compared with non-sinusitis patients. It can be concluded that patients with recurrent sinopulmonary infections and a mild IgG1 subclass deficiency have an impaired IgG1 anti-polysaccharide response, which can extend to decreased IgG2 and IgA anti-polysaccharide responses.  (+info)

IgG2 immunodeficiency: association to pediatric patients with bacterial meningoencephalitis. (5/95)

An IgG subclass deficiency is often associated with bacterial infections. We studied four pediatric patients suffering from meningoencephalitis, two of them due to Streptococcus pneumoniae and two due to Haemophilus influenzae type b. Simultaneous diagnostic serum and cerebrospinal fluid samples were taken during income. The four subclasses of IgG and albumin were quantified in both biologic fluids by radial immunodiffusion. Very low levels of seric IgG2 with non detectable cerebrospinal fluid IgG2 were found in the patients. No intrathecal IgG subclass synthesis was found in two patients. One patient with S. pneumoniae had IgG3 intrathecal synthesis. Intrathecal IgG1, IgG3 and IgG4 synthesis was found in one patient suffering from H. influenzae according with reibergrams. Substitutive therapy with intravenous gammaglobulin was given to the patients as part of the treatment.  (+info)

Fate of the mutated IgG2 heavy chain: lack of expression of mutated membrane-bound IgG2 on the B cell surface in selective IgG2 deficiency. (6/95)

IgG2 deficiency is clinically characterized by sinopulmonary infections caused by pneumococcus and Hemophilus. We reported homozygous one-base insertion (1793insG) in the C(gamma)2 gene in two Japanese siblings in whom serum IgG2 levels were under detection limits. The 1793insG was present in exon 4, just upstream from the alternative splice site for M exons; the result being a complete amino acid change in transmembrane and cytosolic parts of membrane-bound gamma2 heavy chain (m gamma 2HC). To determine why this mutation caused selective and complete IgG2 deficiency, we constructed expression vectors of normal and mutant membrane-bound chimeric IgG heavy chain cDNAs. Stable transformants, Ag8N-L and Ag8M-L, expressing either normal and mutant chimeric IgG heavy chain with light chain respectively were obtained using P3X63Ag8653 as recipient cells. Of the Ag8N-L, 22.1% were surface IgG+; however, none of the Ag8M-L were surface IgG+. Addition of an anti-human IgG antibody induced cell death of Ag8N-L and we considered that the expressed chimeric IgG protein on Ag8N-L might function as the Ig receptor for signal transduction. However, Ag8M-L did not express mutant IgG on its surface nor did it secrete this mutant into culture medium. The mutant chimeric IgG protein was rapidly degraded within Ag8M-L. Thus, the mutated IgG2 heavy chain in our patient could not be expressed on the cell surface because of loss of the transmembrane domain and the evolutionally conserved cytoplasmic domain. In humans, B cells expressing surface IgG are indispensable for secretion of IgG.  (+info)

IgG subclasses in smokers with chronic bronchitis and recurrent exacerbations. (7/95)

BACKGROUND: Tobacco smokers have lower serum levels of IgG than non-smokers. IgG subclass deficiency is common in patients with recurrent respiratory infections. Recurrent bronchial infections are common in smokers with chronic bronchitis (CB). We have investigated whether susceptibility to recurrent exacerbations in smokers with CB is associated with altered IgG subclass levels or IgG subclass deficiency. METHODS: Serum levels of IgG, IgA, IgM, and IgG subclasses 1-4 were determined by radial immunodiffusion in 100 subjects: 33 smokers with stable CB and recurrent exacerbations, 24 asymptomatic smokers, and 43 healthy never smokers. Systemic tobacco exposure was verified and excluded using a serum cotinine ELISA. Immunoglobulin data were log transformed to enable use of parametric statistical methods. RESULTS: Compared with never smokers, both patients with CB and asymptomatic smokers had significantly lower levels of IgG (median 9.7 g/l (range 5.6-15.2) and 9.9 (6.1-12.1) g/l v 12.0 (6.9-18.5) g/l) and IgG2 (2.8 (0.9-5.9) g/l and 2.5 (1.0-6.3) g/l v 4.0 (1.7-10.2) g/l). The estimated ratio of median values between the patients with CB and never smokers was 0.78 (95% confidence interval (CI) 0.69 to 0.89) for IgG and 0.65 (95% CI 0.50 to 0.83) for IgG2. The corresponding ratios between asymptomatic smokers and never smokers were 0.79 (95% CI 0.69 to 0.91) and 0.60 (95% CI 0.50 to 0.83), respectively. There were no significant differences between the smoking groups. CONCLUSIONS: Susceptibility to recurrent exacerbations in smokers with CB is not associated with lower levels of IgG subclasses than can be accounted for by smoking per se.  (+info)

The progressive appearance of multiple urinary Bence-Jones proteins and serum paraproteins in a child with immune deficiency. (8/95)

Multiple urinary Bence-Jones proteins and serum paraproteins were found in a child with type I dysgammaglobulinaemia (Seligmann et al., 1968). These showed a continually evolving pattern over a period of 4 months in relation to systemic infections and with no evidence of underlying malignancy.  (+info)