Variability in generation of anti-sheep erythrocyte plaque-forming cells from cultures of human peripheral blood. Influence of monocytes.

We have encountered two types of variability in the numbers of cells making antibodies in vitro to sheep erythrocytes (PFC) in pokeweed-stimulated human peripheral blood mononuclear lymphocytes (PBM). One is a variation in number of PFC generated by the PBM of one individual compared -o that of another, which is probably an in vitro counterpart to the well known individual variation in in vivo antibody responsiveness and presumed to be T cell controlled. The other variability is in numbers of PFC found in replicate tubes from a given individual. This variation is not T cell controlled, but rather is releated to the relative number of monocytes in the system. Enhancement by monocytes of the numbers of PFC generated is also demonstrated.