The λ B Cell Repertoire of K-Deficient Mice

Abstract

Analysis of the B cell repertoire is complicated by the huge diversity inherent in the germ line determined combinatory. Making use of knockout technology, K-deficient mice have been obtained. They constitute a shrewd model to follow the expression of an Ig minilocus, such as the λ one, in the normal condition compared with classical transgenic models. Indeed, in contrast to wild type mice, in which only 5% of λ B cells are produced, these mutant mice exclusively produce λ positive B cells. Although, the λ locus is well characterized and has a relatively simple organization, the mechanistic and selective pressures that govern its utilization are still poorly understood. The analysis of the λ B cell repertoire in K-deficient mice, should therefore bring more conclusive informations. Here we present the λ subtype distribution in the various cellular compartments of the K-deficient mice, and discuss the rules that can be responsible for this distribution. Our recent data indicate that the λ subtype proportions in the bone marrow and the spleen result, for the major part, from mechanistic processes (i.e., recombinase accessibility, production of V-J functional joint and H/L pairings) while the λ proportions found in the peritoneal cavity ensue from selective processes. Finally, the capacity to respond to various antigens is discussed from such a generated λ B cell repertoire.