FACTORS THAT AFFECT HUMAN HEMATOPOIESIS ARE PRODUCED BY T-CELL GROWTH-FACTOR DEPENDENT AND INDEPENDENT CULTURED T-CELL LEUKEMIA-LYMPHOMA CELLS

Abstract

Human T cells may be important in the regulation of growth of hematopoietic cells. Twenty-four cell lines from patients with cutaneous T-cell lymphoma (CTCL) and T-cell acute lymphoblastic leukemia (T-ALL) were grown with TCGF [T cell growth factor] and then assessed for release of humoral factors that affecte hematopoiesis. Conditioned media (CM) from these cell lines were tested for erythroid burst-promoting activity (BPA) and granulocyte colony-stimulating activity (CSA). BPA was detected in CM from 3/6 cultures of T-ALL patients and 4/6 CTCL cultures. CSA was found in the CM from 6/8 cultures of T-ALL patients, 7/12 CTCL cultures, and 3/4 CTCL cell lines that become independent of exogenous TCGF for growth. The CSA from several of the neoplastic T-cell cultures stimulated high levels of eosinophil colonies, a possible source of the eosinophilia in these patients. The ability of continuously proliferating human T lymphocytes, which retain functional specificity and responsiveness to normal humoral regulation, to produce factors that directly or indirectly stimulate myeloid and erythroid colony formation lends further credence to the role of T lymphocytes in regulating hematopoiesis.