Does positive selection determine the B cell repertoire?
To know whether each newly formed B cell has an equal chance of survival in the organism, we analyzed the composition of the B cell repertoire of extremely limited diversity by generating mu-transgenic kappa-knockout mice. Surprisingly, in both types of mice studied, the B cell repertoire is mainly composed of cells expressing the mu-transgene-encoded chain associated with only one out four available lambda types depending on the mu transgene. Moreover, B cell differentiation cultures in vitro show that newly formed B cells can express the various lambda types regardless of the presence or absence of the mu transgenes. These results show a drastic impact of the heavy chain on the lambda light chain repertoire expressed in the periphery. The overexpression of a unique heavy/light chain pairing therefore results from selective processes. The immature B cells may be positively selected to provide the immunocompetent B cells in the periphery.
Hachemi-Rachedi
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S
Immunochimie Analytique, URA CNRS 1961, Paris, France.
Cumano
A
A
Drapier
A M
AM
Cazenave
P A
PA
Sanchez
P
P
D000818:Animals; D016175:B-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D015328:Gene Rearrangement, B-Lymphocyte, Light Chain; D007146:Immunoglobulin lambda-Chains / Q000235:genetics; D007148:Immunoglobulin mu-Chains / Q000235:genetics; D008070:Lipopolysaccharides / Q000276:immunology; D008213:Lymphocyte Activation / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D012486:Salmonella typhimurium / Q000276:immunology; D019076:Transgenes / Q000276:immunology
D007146:Immunoglobulin lambda-Chains; D007148:Immunoglobulin mu-Chains; D008070:Lipopolysaccharides