A rearranged lambda 2 light gene chain retards but does not exclude kappa and lambda 1 expression.
Mice transgenic for the lambda 2 light chain of MOPC315 were established. In newborn transgenics (TG), lambda 2 was the only light chain found on B cells. However, by day 21, lambda 2 high kappa low as well as lambda 2 low kappa high double expresser populations were emerging. lambda 2 was found on an increased fraction of serum immunoglobulins (Ig), this fraction declined with age. Correspondingly, kappa and lambda 1 expression was suppressed in young mice but increased with age. In adult mice kappa or lambda 1 were often co-expressed with lambda 2 in single serum Ig molecules. Most B cell hybridomas from and adult TG secreted lambda 2,kappa mixed molecules and had rearranged their kappa chain genes. One lambda 2,lambda 1 hybridoma and even a lambda 2,kappa,lambda 1 hybridoma were also found. In conclusion, isotypic exclusion in lambda 2 TG is complete in newborns but becomes increasingly leaky with age. Antigen probably expands the lambda 2 low kappa high B cell population; this population is most likely the major source of serum Ig in adult lambda 2 TG mice. In contrast, the lambda 2 high kappa low population, a major fraction of which is CD5+ Mu low delta low, appears only infrequently to develop into antibody-secreting plasma cells.
Institute of Immunology and Rheumatology, University of Oslo, Norway.
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B
Bogen
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Weiss
D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology; D015870:Gene Expression; D015328:Gene Rearrangement, B-Lymphocyte, Light Chain; D005803:Genes, Immunoglobulin; D006825:Hybridomas; D007132:Immunoglobulin Isotypes / Q000378:metabolism; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D007146:Immunoglobulin lambda-Chains / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism
D007132:Immunoglobulin Isotypes; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; D011947:Receptors, Antigen, B-Cell