Distinct requirements for IL-6 in polyclonal and specific Ig production induced by microorganisms.
The role of IL-6 in Ig production induced in the mouse by lactate dehydrogenase-elevating virus (LDV), Toxoplasma gondii or lipopolysaccharide (LPS) was assessed. Following infection with LDV, a strong activator of B cells, an early and transient IL-6 production was observed, that originated predominantly from macrophages. Whereas LDV-induced B lymphocyte proliferation appeared independent of IL-6, mice deficient for this cytokine showed a marked reduction in their total T-dependent IgG2a production when compared to their normal counterparts. By contrast, specific responses directed against either LDV or non-viral antigens administered at the time of infection were not decreased in the absence of IL-6. Similarly, polyclonal, but not anti-parasite IgG2a production triggered by T. gondii infection was strongly dependent on the presence of IL-6. Finally, T-independent total IgG3 secretion triggered by LPS was also markedly reduced in IL-6-deficient mice. These results suggest that IL-6 plays a major role in T-dependent and T-independent polyclonal Ig production following B lymphocyte activation by viruses, and parasites, but not in specific antibody responses induced by the same microorganisms.
Markine-Goriaynoff
D
D
Unit of Experimental Medicine, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Avenue Hippocrate 74, 1200 Bruxelles, Belgium.
Nguyen
T D
TD
Bigaignon
G
G
Van Snick
J
J
Coutelier
J P
JP
D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D000913:Antibodies, Protozoan / Q000096:biosynthesis*; D000914:Antibodies, Viral / Q000096:biosynthesis*; D000918:Antibody Specificity; D001402:B-Lymphocytes / Q000276:immunology; D004926:Escherichia coli / Q000276:immunology; D005260:Female; D007074:Immunoglobulin G / Q000096:biosynthesis*; D007132:Immunoglobulin Isotypes / Q000096:biosynthesis; D015850:Interleukin-6 / Q000378:metabolism*; D007772:Lactate dehydrogenase-elevating virus / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D014122:Toxoplasma / Q000276:immunology
D000907:Antibodies, Bacterial; D000913:Antibodies, Protozoan; D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D015850:Interleukin-6; D008070:Lipopolysaccharides