Specific antibody-secreting cells generated from cells producing immunoglobulins without detected antibody function

Abstract

STUDIES of immune responses in rabbits, rats and mice have led us to describe a population of differentiated immunocytes synthesising and secreting immunoglobulins without detectable antibody function for the antigens injected¹ (IFC). These cells were antigen induced and appeared before the antibody-forming cells (AFC). The proliferation of IFC after antigenic stimulation can be explained by several hypotheses, the most plausible being that antigen-stimulated T cells release nonspecific factors which trigger clones of B cells bearing membrane receptors unrelated to the inoculated antigen. Such an explanation has been advanced by several authors^2,3 but experiments performed in our laboratory do not support such polyclonal activation. Indeed, some cells contained both antibodies and immunoglobulins without detectable antibody function in different areas of their cytoplasm^1,4. Furthermore, some common idiotypic specificities were expressed by both AFC and IFC (ref. 5). Based on these findings, and additional studies on the developmental kinetics of IFC and AFC in animals with different immunological status, which indicate that there is a close relationship between these two cell populations, we put forward the hypothesis that AFC might be recruited among IFC. That is, that these two cell types represent two stages of differentiation of the same cell population. To test this assumption directly we performed experiments at the single cell level with micromanipulated and individually cultured IFC and found that at least some of these cells generate specific AFC.