Clonal anergy: Persistence in tolerant mice of antigen-binding B lymphocytes incapable of responding to antigen or mitogen

Publisher Website
Google Scholar
Abstract
The degree of reduction in the number of antigen-binding B [bone marrow-derived] lymphocytes in the spleens of mice that were rendered tolerant in the perinatal period was determined. Newborn or pregnant mice were injected with fluorescein (Flu) coupled onto human .gamma.-globulin, and the spleen cells of the neonatally injected mice or of the offspring of the pregnant mice were analyzed 1-6 wk later. Tolerogen doses were chosen so as to achieve a 2/3 reduction (low dose) in the number of anti-Flu B cells capable of yielding anti-hapten plaque-forming cell clones after in vitro stimulation, or as representing a supraoptimal tolerogenic stimulus (high dose). Antigen-binding B cells were studied by a 2 cycle procedure, namely an initial cycle of binding to Flu-gelatin thin layers, followed by analysis of the binding cells in the fluorescence-activated cell sorter (FACS) after suitable staining with Flu-protein conjugates. With the high dose of tolerogen, a modest diminution in Flu-binding cell numbers down to 56-71% of control values could be induced. When these residual Flu-specific B cells were analyzed in the FACS to quantitate their spectrum of Flu-binding avidities, profiles identical to those of controls were obtained. The reduction was transient, binding cell numbers returning to 80% of normal by 2 wk and to normal by 6 wk. Flu-specific B cells were incapable of responding to antigen or mitogen by antibody formation. With the low dose of tolerogen, despite the desired degree of functional silencing of Flu-specific B cells, the numbers and avidity spectra of antigen-binding cells were entirely normal in the neonatally injected and in utero-injected groups. Thus, tolerance induced among immature B lymphocytes is not due to a physical elimination of the relevant B cell clones or to a modulation or blockade of their surface Ig [immunoglobulin] receptors. Rather, it is due to the recognition and storage of negative signals among cells that continue to display a normal complement of receptors. The term clonal anergy is thus a more accurate description than clonal deletion or clonal abortion.