Transformation of human umbilical cord blood T cells by human T-cell leukemia/lymphoma virus.

Several isolates of human T-cell leukemia/lymphoma virus (HTLV) were transmitted to normal human T cells obtained from the umbilical cord blood of newborns. T cells from seven specimens were immortalized by infection with different HTLV isolates and their properties were compared with those of activated uninfected normal T cells grown in the presence of T-cell growth factor (TCGF) and with those of HTLV-positive neoplastic T-cell lines derived from patients with T-cell malignancies. The HTLV-infected cells generally belonged to a class of mature T cells (OKT4+ and Leu 3A+) and differed from the normal uninfected cells in that they could be propagated in culture indefinitely; possessed altered morphology, including convoluted nuclei and some bi- and multinucleated giant cells; formed large clumps in culture; demonstrated a diminished requirement for TCGF; had an increased density of TCGF receptors; often became completely independent of exogenous TCGF; and expressed HLA-DR determinants. These properties of the HTLV-infected cord blood T cells contrasted to those of uncultured cord blood T cells and of cord blood cells stimulated with mitogen and grown with TCGF but resembled the characteristics of T-cell lines established previously from patients with HTLV-associated T-cell malignancies. This in vitro system offers a unique opportunity to study the basic mechanism involved in abnormal growth and neoplastic transformation of a specific class of human T cells.