CELLULAR COOPERATION IN LYMPHOCYTE-ACTIVATION .1. COOPERATIVE AND NON-COOPERATIVE RESPONSES OF HUMAN T-LYMPHOCYTES AND B-LYMPHOCYTES TO VARIOUS MITOGENS

Human T and B lymphocytes were highly purified from tonsil and peripheral blood, and their proliferative responses to various mitogens were studied. T cells [T(III)] were purified by filtration through a nylon fiber column (NC), followed by a double cycle of E rosette formation and Ficoll-Paque sedimentation. B cells [B(VIII)] were obtained from the NC-retained fraction by twice removal of E rosette forming cells. A second T cell preparation [T(VI)] was obtained from the NC-retained fraction. Purified T(III) and B(VIII) preparations contained less than 1% of other cell types. Phytohemagglutinin, pokeweed mitogen and concanavalin A (T mitogens) stimulated T(III) and T(VI) well, but had no effect upon B(VIII). Staphylococcus aureus Cowan I (SpA) and insolubilized protein A stimulated B(VIII) in the complete absence of T cells. Under the reconstituted culture of T(III) and B(VIII), responses to T mitogens were greatly enhanced by the addition of B(VIII). This enhancing effect was mainly caused by B cells and was not diminished by mitomycin treatment, suggesting that the observed T-B cooperation was attributable to direct cell-to-cell interaction. B(VIII) were also significantly stimulated by T mitogens in the presence of smallest number of T cells. SpA stimulated B(VIII) in proportion of their cell number independent of the addition of T cells. On the other hand, T(VI), which contained 3-10% B cells, showed rather higher response to T mitogens than T(III), failed to show coorepation with B(VIII). © 1979 S. Karger AG, Basel.