Differential regulation by Ly-5 and Lyb-2 of IgG production induced by lipopolysaccharide and B cell stimulatory factor-1 (IL-4).
We have previously shown that mAb Ly-5 which on B cells recognizes a 220,000-Da (B220) molecule, inhibits LPS-induced IgG responses without affecting IgM or proliferative responses, whereas mAb Lyb-2 which modulates B cell activation processes induced by B cell stimulatory factor-1 (BSF-1) or IL-4, has no effect on LPS-induced B cell responses. In this report we further examined the cellular mechanisms of Ly-5 antibody action and the effect of Lyb-2 antibody in IgG responses induced by LPS and BSF-1. The results presented demonstrated that the inhibitory effect of Ly-5 antibody seems to be restricted to the IgG class and is observed in all IgG subclasses induced by LPS. Limiting dilution analysis showed that the Ly-5 antibody reduces primarily the precursor frequency of IgG-secreting cells and that the effect on the clone size is partial. Lyb-2 antibody, on the other hand, greatly inhibited IgG1 induction initiated by LPS and BSF-1 by the action on processes triggered by BSF-1, although it could not reverse the reduced IgG2b or IgG3 responses. Limiting dilution analysis revealed that Lyb-2 antibody reduces the precursor frequency but not the clone size of BSF-1-induced IgG1-producing cells, supporting our previous proposition that Lyb-2 plays a critical role in the B cell differentiation mediated by BSF-1. Taken together, these results indicate that both Ly-5 and Lyb-2 are important molecules in IgG subclass regulation, each acting on a distinct activation step.
Yakura
H
H
Department of Pathology, Asahikawa Medical College, Japan.
Kawabata
I
I
Ashida
T
T
Katagiri
M
M
D000818:Animals; D000911:Antibodies, Monoclonal / Q000502:physiology; D000950:Antigens, Ly / Q000276:immunology*; D001402:B-Lymphocytes / Q000145:classification / Q000276:immunology* / Q000378:metabolism; D002999:Clone Cells / Q000276:immunology; D007074:Immunoglobulin G / Q000096:biosynthesis*; D007153:Immunologic Deficiency Syndromes / Q000235:genetics; D007166:Immunosuppressive Agents / Q000502:physiology; D015847:Interleukin-4; D007378:Interleukins / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D013234:Stem Cells / Q000276:immunology; D013997:Time Factors
D000911:Antibodies, Monoclonal; D000950:Antigens, Ly; D007074:Immunoglobulin G; D007166:Immunosuppressive Agents; D007378:Interleukins; D008070:Lipopolysaccharides; D015847:Interleukin-4