Spontaneous immunoglobulin A secretion and lack of mitogen-responsive B cells in systemic lupus erythematosus.
In an analysis of lymphocyte functions of systemic lupus erythematosus (SLE) patients, B cell abnormalities such as a lack of mitogen-responsive B cells and a predominance of spontaneous IgA-secreting cells (SC) were found. Lymphocyte functions of 20 SLE patients were studied. Impaired proliferative response to B cell mitogen, Staphylococcus aureus strain Cowan I (Cowan I), was observed, whereas the response to T cell mitogen phytohemagglutinin was normal. High levels of spontaneous IgA-SC were observed in SLE patients (greater than 10(2) cells/10(4) peripheral blood mononuclear cells [PBMC]), whereas spontaneous IgM-, IgG-, or IgE-SC were not proportionately increased. The number of spontaneous IgA-SC decreased with time in culture and became undetectable by day 5 of culture. In contrast, spontaneous immunoglobulin- (IgM, IgG, and IgA) SC were not observed in healthy volunteers (less than 10 cells/10(4) PBMC). Moreover, in SLE patients failure of induction of immunoglobulin-secreting cells (ISC) was observed when B cells were stimulated by Cowan I and B cell differentiation factor at any day tested, whereas ISC were induced in healthy volunteers on day 6 of culture. Depletion of T cells or macrophages did not affect the results obtained. These results suggest that the abnormalities observed in SLE B cells are not due to the in vitro direct effects of suppressor macrophages or suppressor T cells, and that the condition of the predominance of spontaneous IgA-SC and the unresponsiveness to exogenous stimulation may be emblematic of hyperactive B cells in SLE.
D000921:Antibody-Producing Cells / Q000276:immunology*; D000944:Antigens, Differentiation, B-Lymphocyte; D000954:Antigens, Surface / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000378:metabolism*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008213:Lymphocyte Activation; D010835:Phytohemagglutinins / Q000276:immunology; D013211:Staphylococcus aureus / Q000276:immunology
D000944:Antigens, Differentiation, B-Lymphocyte; D000954:Antigens, Surface; D007071:Immunoglobulin A, Secretory; D010835:Phytohemagglutinins