Polyclonal and antigen-specific B-Cell responses in patients with common variable immunodeficiency

Antigen-specific antibody responses were investigated in 32 hypogammaglobulinemic patients with common variable immunodeficiency following in vitro sensitization of their peripheral blood lymphocyte cultures with sheep red blood-cell determinants. Anti-sheep red blood-cell antibody-secreting cells were quantitated in a hemolytic plaque assay. Amplification of T-cell help was achieved with the use of the T-cell mitogen concanavalin A or allogeneic irradiated T cells. Four patients groups, A through D, were identified. Group A was comprised of 10 patients whose cultured lymphocyte readily developed into antibody secreting cells. Cultures of 9 patients (Group B) responded suboptimally, but were enhanced following mitogen activation of autologous or exogenous T cells, and those of 7 patients (Group C) responded only when help was aplified. In 7 patients (Group D), no responses were elicited. On the simultaneous assessment of pokeweed mitogen-driven polyclonal generation of immunoglobulin-secreting cells, only 10 responders, all from groups A and B, were identified. Our observations indicate that the majority of patients with common variable immunodeficiency possesses B cells capable of producing antibody in vitro. The ability of some patients' B cells to respond only in the antigen-specific assay while failing to do so in pokeweed mitogen-stimulated cultures suggests that these two reactions are not identical in their activation pathways.