Expression of b 4 and b 5 ϰ light chain allotypes by B and pre‐B cells in allotype‐suppressed and neutralized b⁴b⁵ rabbits

Abstract

Abstract In previous studies, we described a primitive lymphoid cell found in fetal liver and in the bone marrow of older rabbits which contained cytoplasmic IgM but lacked surface IgM detectable by immunofluorescence. In heterozygous b 4 b 5 rabbits, the pre‐B cells in which we could detect these kappa chain allotypes appeared to exhibit allelic exclusion. In the present study, we investigated the effects of allotype suppression and its neutralization on the expression of the b4 and b5 allotypes by B and pre‐B cells from the spleens and bone marrow of b 4 b 5 rabbits. We found that in young allotype suppressed rabbits, pre‐B cells of the suppressed allotype persist in bone marrow when B cells of the suppressed allotype are absent or severely depleted. The persistence of pre‐B cells of the suppressed type supports the view that pre‐B cells differ in their responsiveness to external influences such as anti‐Ig compared to B lymphocytes. Injection of serum with b5 immunoglobulin into b 4 b 5 animals suppressed 14‐23 days previously for b5 was followed by the appearance of increased proportions of b 5 B cells in spleen within 24 h. Surviving pre‐B cells are a likely source of these rapidly appearing B cells as well as of the B cells bearing surface immunoglobulin of the suppressed allotype which appear during the recovery phase of allotype suppression.