1982 Volume 5 Issue 1 Pages 66-75
A polyclonal B cell mitogen, formaldehyde-fixed Staphylococcus aureus Cowan I (SpA CoI) bacteria, stimulated proliferative response of human B cells and induced large quantity of IgM, G and A production. Proliferative response and Ig production by SpA CoI bacteria was independent of the presence of T cells.
Various B cell subsets from tonsil and peripheral blood were separated regarding complement receptor (C3R), IgG-Fc receptor (FcR) or surface immunoglobulin (SIg) on their surface using various rosette formation techniques. Which of the B cell subsets were activated by the stimulant was investigated in detail. Marked increase in the SpA CoI-induced proliferative response and Ig production was observed in C3R+ cells but not in C3R- cells. It was also shown that FcR- cells responded to SpA CoI bacteria more strongly than FcR+ cells. While SIg- cells failed to respond to SpA CoI bacteria, SIg+ B cells responded markedly to the stimulant. Among the SIg+ B cell subsets, in particular, IgM+ and IgG+ B cells showed a marked response to the stimulant and much less response was seen in IgA+ and IgD+ B cells.
These results indicate that B cell subsets responding to SpA CoI bacteria were characterized as C3R+, FcR- and SIg+ (in particular IgM+ and IgG+) B cells, which belonged to immature or young B cells. SpA CoI bacteria was thus capable of differentiating these B cells into mature B cells and plasma cells and was proved to be a useful tool in the study of the maturational development and differentiation.
