Endothelial cell enhancement of PWM induced immunoglobulin synthesis by peripheral blood mononuclear cells

The effect of various exogenous cells on the in-vitro PWM stimulation of immunoglobulin synthesis by normal human peripheral blood mononuclear cells was investigated. The accessory cells tested were bovine and human endothelial cells, bovine and human fibroblasts, normal human monocytes, and a monocyte cell line U937. Bovine and human endothelial cells boosted PWM-induced IgG and IgM synthesis, sometimes threefold. The enhancement was maintained over the 7-11 day period of culture and probably required cell to cell contact. It was not seen with the other cell types added and was, therefore, unlikely to be a consequence of an allogeneic or a xenogeneic stimulation, or a nonspecific 'feeder cell' effect.