The roles of preB and B cell receptors in the stepwise allelic exclusion of mouse IgH and L chain gene loci.
Membrane-bound preBCR of wild-type mice, and probably also preBCR-like V(preB) muH chain complexes in lambda5-deficient mice, signal allelic exclusion so that < 0.1% of all preB-II cells and all subsequent B lineage cells express two muH chains on their surface. On the other hand a large number of muH chains which are originally generated at the transition of preB-I to preB-II cells cannot pair with surrogate L chains, cannot form a preBCR on the surface and, hence, allow two H chain alleles to be productively rearranged in one B-lineage cell. By contrast membrane-bound BCR on immature B cells does not signal allelic or isotypic exclusion Of Ig kappaL and lambdaL chain gene loci. This allows the rearrangement machinery to remain active, and secondary L chain rearrangements on one kappaL chain allele are frequently observed. Rapid selection of fitting H/L chain pairs, forming BCR on the surface, allows B-lineage cells to enter the mature B cell pool where the rearrangement machinery is shut off, securing allelic exclusion of L chain loci in most B cells.
Melchers
F
F
Basel Institute for Immunology, Basel, Postfach, 4005, Switzerland.
ten Boekel
E
E
Yamagami
T
T
Andersson
J
J
Rolink
A
A
D000483:Alleles; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology*; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D015328:Gene Rearrangement, B-Lymphocyte, Light Chain; D006801:Humans; D051379:Mice; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*
D011947:Receptors, Antigen, B-Cell