Augmentation of Pha Responsiveness in Mixed Thymus-Marrow Cultures

Abstract Only minimal increments of 3HTdr uptake were demonstrated in PHA-stimulated cultures of normal guinea pig thymocytes. Bone marrow cultures from both normal and erythroid suppressed animals failed to proliferate in response to this nonspecific stimulus. However, the combination of thymic and marrow cells resulted in significant augmentation of PHA responsiveness. Maximum synergistic activity occurred when thymus and marrow cells were cultured in equal amounts. The in vitro behavior of thymus and marrow cells alone and in combination is consistent with their immunologic activity in the intact animal.