Rituximab may form a complex with IgMkappa mixed cryoglobulin and induce severe systemic reactions in patients with hepatitis C virus-induced vasculitis.
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Cold agglutinins in haemophiliac boys infected with HIV.
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Eleven haemophiliac boys infected with HIV were screened for irregular red cell antibodies and were compared with nine haemophiliac boys who did not have antibodies to HIV. Seven (64%) of the children who had antibodies to HIV also had cold agglutinins, mostly of anti-I specificity, compared with one (11%) of those who did not have antibodies to HIV. The children with antibodies to HIV and cold agglutinins had a significantly increased mean IgM concentration. The presence of cold agglutinins was not correlated with T4 lymphocyte count, symptoms of HIV infection, serum beta 2 microglobulin concentrations, concentrations of IgG or IgA, or with the evidence of past infection with cytomegalovirus or Epstein-Barr virus. (+info)
Quantification of cross-reactive idiotype-positive rheumatoid factor produced in autoimmune rheumatic diseases. An indicator of clonality and B cell proliferative mechanisms.
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The aetiology of sustained autoantibody production in human autoimmune diseases is unknown. Evidence for structural similarities and common clonal origin among autoantibodies have been demonstrated through the expression of cross-reactive idiotype (CRI). In the present study we use four monoclonal antibodies (MoAbs) with specificity for non-overlapping CRI on human rheumatoid factor (RF) autoantibodies to define the structural features of polyclonal RF characteristic of patients with autoimmune rheumatic diseases. The pattern of CRI expression in the serum of 12 patients with rheumatoid arthritis (RA), eight with systemic lupus erythematosus (SLE) and 20 with primary Sjogren's syndrome and 34 normal individuals were determined in parallel with the level of IgM RF, IgA RF and autoantibodies to the cellular antigens SS-A, SS-B, Sm, nRNP and dsDNA and cryoglobulins. The results demonstrate significant elevation in the level of IgM and IgA expressing VHI (G6 and G8) and VHIII (B6 and D12) associated CRI in the serum of patients with autoimmune rheumatic diseases compared with normal individuals. These increases paralleled, but did not equal the increase in the level of immunoglobulins and RF. However, when expressed as proportion of immunoglobulin, only the VHI-associated CRI were significantly elevated in patients compared with normal individuals. The proportion of IgM RF expressing the VHI-associated CRI was higher in patients with Sjogren's syndrome compared with SLE and RA. Furthermore, the proportion of IgA RF expressing the G6 CRI was higher than G6+ IgM RF. These findings imply that different mechanisms contribute to RF production in autoimmune diseases. It is suggested that polyconal B cell activation is likely to be a contributing mechanism. However, such polyclonal activation is unlikely to be random since a selective elevation in the level of specific autoantibodies and VHI-associated CRI is observed. Furthermore, the data demonstrate that a proportion of autoantibodies in autoimmune diseases are immunoglobulin germline gene encoded. This is more evident in some patients with primary Sjogren's syndrome, where RF is likely to be oligoclonal or monoclonal in individuals with lymphoproliferation. (+info)
Association of serum IgM kappa monoclonicity in patients with Sjogren's syndrome with an increased proportion of kappa positive plasma cells infiltrating the labial minor salivary glands.
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Minor salivary gland biopsy specimens from 11 patients with primary Sjogren's syndrome with circulating monoclonal IgM kappa cryoglobulins, seven without cryoglobulins, and four patients with rheumatoid arthritis and Sjogren's syndrome (one with monoclonal and three with polyclonal cryoglobulins) were examined by the peroxidase antiperoxidase bridge technique, using antihuman kappa and lambda antibodies. In 6/11 patients with primary Sjogren's syndrome and in one patient with Sjogren's syndrome and rheumatoid arthritis with monoclonal cryoglobulins a predominance of plasma cells containing intracytoplasmic kappa light chains was found (kappa:lambda greater than 3:1). Two of those seven patients had immunohistological features of immunocytomas. In the other five patients with circulating monoclonal cryoglobulins the kappa:lambda ratio of positive cells did not exceed 3:1, while six out of seven patients without cryoglobulins and the patients with rheumatoid arthritis and Sjogren's syndrome with polyclonal cryoglobulins had almost equal numbers of kappa and lambda stained cells. One of seven patients with primary Sjogren's syndrome without cryoglobulins had an increased number of lambda light chain positive cells, indicating a non-secretory lambda monoclonal population. These findings suggest that the main area of B cell monoclonal expansion in primary Sjogren's syndrome may be the affected exocrine glands. (+info)
The limitations of IgM assays in the serological diagnosis of Mycoplasma pneumoniae infections.
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The most useful and reliable serological investigations for the diagnosis of current Mycoplasma pneumoniae infection, including reinfection, were investigated. Paired sera and respiratory specimens from 115 patients with lower respiratory tract symptoms were examined for evidence of current M. pneumoniae infection by serological response, as measured by complement-fixation and indirect immunofluorescence tests for specific IgM, IgA and IgG, and also by culture of M. pneumoniae from respiratory material. Specific IgM was not always detectable in cases where other criteria indicated current or recent infection. On the basis of the present results, it is postulated that primary infection and reinfection may be differentiated by the presence or absence of specific IgM in the presence of elevated specific IgA levels and, therefore, that estimation of both IgM and IgA is necessary for the maximal detection of current M. pneumoniae infection, including reinfections. Specific IgG levels remained elevated for many weeks and were not useful diagnostically. (+info)
Prevalence and clinical significance of cryofibrinogenaemia in patients with renal disorders.
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Polymorphonuclear leucocyte fluorescence and cryoglobulin phagocytosis in systemic lupus erythematosus.
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Peripheral blood polymorphonuclear leucocytes (PMN) and cryoglobulins were isolated from patients with systemic lupus erythematosus (SLE). Fluorescent inclusions were found in PMN. Normal donor PMN were incubated with the sera and cryoglobulins from SLE patients. In most cases inclusions were observed after incubation. The high incidence of anti-IgG activity in phagocytosed cryoglobulins confirms the importance of the rheumatoid factor in phagocytosis of immune complexes. It is concluded that phagocytosis of cryoglobulins supports the suggestion that cryoglobulins are a subpopulation of immune complexes. (+info)