Peritoneal Ly-1 B cells: genetic control, autoantibody production, increased lambda light chain expression.

Previous studies demonstrate that Ly-1 B cells and their progenitors are clearly detectable in peritoneum in normal mice. In this publication, we show (a) that peritoneal Ly-1 B cells resemble splenic Ly-1 B cells with respect to surface marker expression and functional activity (autoantibody production); (b) that Ly-1 B frequencies in peritoneum are considerably higher than in spleen; and (c) that genetic mechanisms reduce peritoneal Ly-1 B frequencies to minimal levels in SJL-related mice and to below detectability in CBA/N and other mice with the X-linked immunodeficiency (Xid). In addition, we show that that peritoneal (and perhaps splenic) Ly-1 B populations demonstrate an unique bias in immunoglobulin commitment. That is, they are selectively enriched for cells that express IgM heavy chains in association with lambda light chains. Thus, as a whole, evidence presented here defines the peritoneum as a tightly regulated lymphocyte compartment that normally houses a large population of mature Ly-1 B cells with distinctive functional properties.