title: Lead, a major environmental pollutant, is immunomodulatory by its differential effects on CD4+ T cells subsets.
abstract: Studies were undertaken to address the necessity of B-T cell contact for the enhancement of B cell differentiation caused by the heavy metal lead (Pb). Membrane segregated cultures were used so that the influences of direct B-T cell contact and T cell factors on B cell differentiation could be independently evaluated. B-T cell contact was not absolutely required for Pb's enhancement of B cell maturation to antibody forming cells (AFCs); however, enhancement of the AFC response by Pb was optimal when B-T cell interactions were allowed. These results were corroborated by use of anti-L3T4 (mouse CD4) to block CD4+ T cell-B cell interaction. Blockade of B-T cell contact with anti-L3T4 did not inhibit the enhancement of the AFC response by Pb. Additional experimentation showed that Pb enhanced the AFC response and Ig production in the presence of antigen-specific T cell help, suggesting that Pb enhances B cell differentiation by augmenting cognate help rather than by inducing a response to Pb-altered-self. In studies employing antigen-specific T cell clones, Pb was found to differentially modulate antigen presentation to TH1 versus TH2 T cell clones, in that TH1 activation was inhibited and TH2 activation was enhanced by Pb.
authors.affiliation: Department of Microbiology and Immunology, Albany Medical College, New York 12208.
authors.forename: M J
authors.initials: MJ
authors.lastname: McCabe
authors.forename: D A
authors.initials: DA
authors.lastname: Lawrence
mesh_terms: D000818:Animals; D000921:Antibody-Producing Cells / Q000187:drug effects; D000938:Antigen-Presenting Cells / Q000187:drug effects; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects; D015704:CD4 Antigens / Q000276:immunology*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D004785:Environmental Pollutants / Q000009:adverse effects; D000939:Epitopes; D005260:Female; D007136:Immunoglobulins / Q000096:biosynthesis; D007854:Lead / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D008815:Mice, Inbred Strains; D016176:T-Lymphocyte Subsets / Q000187:drug effects* / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000502:physiology; D006377:T-Lymphocytes, Helper-Inducer / Q000187:drug effects* / Q000276:immunology
chemical_list: D015704:CD4 Antigens; D004785:Environmental Pollutants; D000939:Epitopes; D007136:Immunoglobulins; D007854:Lead