Expression of surface membrane IgG on pokeweed mitogen-reactive anti-tetanus toxoid antibody-producing cells

Abstract

Anti-tetanus toxoid antibody-producing cells, differentially expressing surface membrane IgM, were analyzed for the additional expression of surface membrane IgG. μ⁺ and μ⁻ cells were rosetted with anti-γ-ox red blood cells and separated by density centrifugation into fractions enriched or depleted or γ⁺ cells. These B-cell subsets were assayed for the production of IgM and IgG anti-tetanus toxoid antibody and total IgM and IgG. The results indicated that the majority of anti-tetanus toxoid antibody synthesis in the μ⁻ fraction was by γ⁺ cells. In the μ⁺ fraction, however, both IgM and IgG anti-tetanus toxoid antibody production was detected in the μ⁺γ⁻ and μ⁺γ⁺ fraction. The inclusion of isotype-specific antisera during the first 2 days of culture further established that γ was expressed on the surface of the majority of the precursors for IgG anti-tetanus antibody productionin vitro. Studies performed to determine the culture requirements of μ⁻ and μ⁺ cells revealed that production of IgG anti-tetanus toxoid antibody by both cell subsets was dependent on T cells and pokeweed mitogen. However, some μ⁻ cells could produce IgG in the presence of T cells alone.