Human T-Cell Growth Factor, Growth of Human Neoplastic T Cells, and Human T-Cell Leukemia-Lymphoma Virus

Abstract

Identification of conditions permitting growth of different human hematopoietic cell strains was a goal for a long time in many laboratories including ours. To this end we screened a large number of sources including conditioned media from freshly initiated cultures of a variety of tissue and cell types for factors that would support growth of specific hematopoietic cell types in suspension culture. These attempts led to the initial description of an activity in the media from short-term cultures of human peripheral blood lymphocytes treated with phytohemagglutinin (PHA) that allowed the specific growth of T lymphocytes from human peripheral blood or bone marrow (Morgan et al., 1976; Ruscetti et al., 1977). Extensive characterization of the resultant cell population revealed that these were functional T lymphocytes (Ruscetti et al., 1977), and the term “T-cell growth factor” (TCGF) was assigned to the activity. Preliminary analyses quickly revealed that the T-cell response is a two-step process: an initial activation of the lymphocytes by lectin (or an antigen) which makes the cells synthesize receptors for TCGF and subsequently bind TCGF resulting in the mitogenic activity. The effect was highly specific and the only cells that grew out of the mixed population of cells that we started with were cells with morphological and functional characteristics of mature T cells and only after preliminary activation with PHA.