The heavy metal lead exhibits B cell-stimulatory factor activity by enhancing B cell Ia expression and differentiation.
Lead (Pb) has been shown to enhance B cell differentiation and to induce T cell proliferation in vitro. Our work demonstrates a direct enhancing effect of Pb on IgM production by T cell depleted-, LPS-activated B cells. Pb also caused a significant, dose-dependent increase in the B cell surface density of both products from the I-region of the murine MHC, I-A and I-E, that was comparable to and within the same time frame as other conventional B cell activators. Pb did not alter B cell surface density of MHC class-I molecules, but it did modulate the levels of other relevant activation Ag such as sIgD and Fc epsilon R. The modulation of the B cell phenotype caused by Pb was not due to release of IL-4 from residual T cells or endotoxin contamination of any culture reagents. Hg also increased cell surface MHC class II molecule density; however, neither Ni, Zn, nor Cd modulated Ia, indicating that immunomodulatory metals have different mechanisms of action. These results suggest that the mechanism of Pb immunopotentiation might be due to increased B-Th cell collaboration and that Pb can act as a B cell stimulatory factor. In addition to the obvious environmental implications of these results, determining Pbs mechanism of action on B cells may yield important information relevant to B cell activation in general.
McCabe
M J
MJ
Department of Microbiology and Immunology, Albany Medical College, NY 12208.
Lawrence
D A
DA
D000818:Animals; D000917:Antibody Formation / Q000187:drug effects; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis; D001402:B-Lymphocytes / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D006183:H-2 Antigens / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D015847:Interleukin-4 / Q000378:metabolism; D007854:Lead / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008815:Mice, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology
D000944:Antigens, Differentiation, B-Lymphocyte; D006183:H-2 Antigens; D000949:Histocompatibility Antigens Class II; C024138:I-E-antigen; D008070:Lipopolysaccharides; D015847:Interleukin-4; D007854:Lead