An idiotype-specific helper population that bears immunoglobulin, Ia, and Lyt-1 determinants.

Abstract

Most helper populations that specifically regulate immune responses are Lyt-1 + T lymphocytes specific for carrier or idiotypic determinants (1-5). These T lymphocytes perform a major role in the regulation of antigen-specific immune responses. In contrast, the role of B cells as regulators of the immune response has been less well established. There has been one report demonstrating that an Lyt-1 +, Ig + B cell subpopulation can augment the plaque-forming cell (PFC) 1 response in an Igh-restricted fashion, suggesting a regulatory role for such unique B cell subsets (6).This report presents evidence supporting the existence of a similar regulatory B cell-like population in the (4-hydroxy-3-nitrophenyl)acetyl hapten (NP)-specific PFC response. This Ig +, Lyt-1 + helper population, termed Bn, is present in normal unprimed mice and specifically augments the PFC response of NP b idiotype-bearing B cells in the absence of T helper populations. The Bn population functions in an Igh-restricted fashion and specifically binds to Npb-idiotypic determinants, suggesting that Bn-mediated regulatory interactions are dependent on idiotype-antiidiotype complementation.

A rheumatoid arthritis b cell subset expresses a phenotype similar to that in chronic lymphocytic leukemia

“…It is possible that this population represents an early stage of differentiation of the immature ("virgin") B cells (9). (12,21) and are capable of amplifying the production of specific antibody (21) with a restricted idiotype through B-B cell interaction (22). In 1 experimental model of autoimmunity (NZB and NZB-related strains of mice), Ly-1 B cells are expanded in the spleen and have been shown to spontaneously secrete IgM autoantibodies in vitro (12,13,23).…”

Unusual phenotype of B cells in the thymus of normal mice.

“…These B cells appear early in development (11) and are long lived (12) . A regulatory role has been suggested in allotypic (13) and idiotypic cell-cell interactions (14)(15)(16). This being the case, it is possible that the Ig V region of thymic Ly-1 B cells shapes the repertoire of T cell antigen receptors by providing epitopes that correspond to antigen in association with self- of the Ly-1 B cell subset, which was identified previously as a trace subpopulation in some peripheral tissues and is thought to play a role in autoantibody formation .…”

B lymphocyte reconstitution after human bone marrow transplantation. Leu-1 antigen defines a distinct population of B lymphocytes.

“…Furthermore, Ly-I B cells do not respond to immunization with production of specific antibodies, and they may be able to provide allotypic and idiotypic helper cell function to suboptimal numbers of Th cells in a secondary immune response. It has been suggested that the tendency to produce anti-idiotype antibody and lymphokines is related to their possible function in the control of Ig synthesis (22)(23)(24)(25). Numbers of Ly-l B cells diminish with the aging of mice (21).…”

“…There are functional similarities and differences between human fetal spleen Leu-1+ B cells and murine Ly-l B cells. In the mouse these cells are constitutive producers of IgM that tend to have autoimmune reactivity, but do not proliferate or produce specific antibodies in response to lectins or to immunization (21), and they augment the helper effects of suboptimal numbers of Th cells in a seccondary immune response (22)(23)(24); perhaps, in part due to the production of lymphokines (22,25). In human fetuses, Leu-lI B cells do not proliferate in response to lectins or constitutively produce IgM.…”