Abstract
Conditioned medium derived from peripheral mononuclear low-density cells stimulated with phytohemagglutinin (PHA) supports the growth of noncommitted hematopoietic progenitors from marrow and peripheral blood cells. These immature progenitors (CFU-GEMM) can be identified in culture as multilineage hematopoietic colonies containing erythroblasts, eosinophilic, basophilic and neutrophilic granulocytes, megakaryocytes, macrophages, and T and B lymphocytes. In this report, we describe the effect of lymphokines released from purified T lymphocyte preparations of helper (T4) and suppressor/cytotoxic (T8) phenotype derived from peripheral blood on the growth of multilineage hematopoietic colonies and megakaryocytic colonies. It was found that PHA-stimulated lymphocytes of T4 phenotype and, to a lesser extent, of T8 phenotype elaborate lymphokine(s) that support the growth and development of multilineage colonies (CFU-GEMM), granulopoietic colonies (CFU-C), erythroid bursts (BFU-E) and megakaryocytic colonies (CFU-M) by nonadherent and T cell-depleted bone marrow cells.
