The ontogeny of B lymphocytes IV. Induction signals mediating phenotypic conversion of PC.1− to PC.1+B cells

✍ Scribed by U. Hämmerling; Ann F. Chin

• Publisher: John Wiley and Sons
• Year: 1977
• Tongue: English
• Weight: 580 KB
• Volume: 7
• Category: Article
• ISSN: 0014-2980
• DOI: 10.1002/eji.1830070808

✦ Synopsis

Abstract

The present study presents evidence that spleen and lymph node cell populations contain a distinct subpopulation of B lymphocytes amounting to < 1 % of the total, which are committed and poised to the expression of the PC. 1 alloantigen, and which can be triggered in vitro to express PC.1. The pheno‐type of the PC.l‐inducible cells has been determined as Ig^+^ Ia^+^ complement receptor (CR)^+^ PC.l^−^ which characteristically is associated with mature lymphocytes. Since the PC.l alloantigen identifies plasmacytes, the induction experiments imply that the latter cells are in principle descendents of CR^+^ B lymphocytes.

The induction signal mediating PC.l^−^ to PC.1^+^ conversion is different from that mediating early pro‐B cell induction. Inducing agents of PC.l^−^←PC.1 ^+^ include carbamylcholine, thymopoietin, prostaglandin F~2α~ and 8‐bromo cyclic GMP, all of which have previously been shown to inhibit early pro‐B cell induction. Conversely, most agents inducing phenotype conversion in early pro‐B cells (e.g. lipopolysaccharide, tumor‐necrotizing serum, isoproterenol, prostaglandin E^1^ and dibutyryl cyclic AMP) are strong inhibitors of PC. 1 induction. The results suggest that inducible B lymphocytes are under dual control of agents imparting opposing signals to them, but that the mode in which they respond is reversed when they have matured to the CR^+^ state. Since PC. 1 expression coincides largely with differentiation to antibody‐forming cells, the reversal of responses to regulatory signals may be of significance as a safeguard against spurious activation of B lymphocytes.