Persistent in vitro infection by human T‐cell leukemia‐lymphoma virus (HTLV) of normal human T‐lymphocytes from blood relatives of patients with HTLV‐associated mature T‐cell neoplasms

Abstract

Human T-cell lymphoma-leukemia virus (HTLV), a novel type-C retrovirus, has been identified in tumor cells of patients with mature T-cell neoplasms. Attempts to transmit the first isolate of HTLV designated HTLV-I , , , to secondary cultures of animal cells and several attempts to transmit HTLV t o normal human T cells, activated with PHA and grown with T-cell growth factor (TCGF), obtained from randomly selected normal adult donors were unsuccessful. Peripheral blood leukocytes were obtained from blood relatives of patients with HTLV-positive T-cell neoplasms. These normal adult T cells were exposed to HTLV, and in 5 of 10 samples tested from three separate families, persistent infection of cultured Tlymphocytes by HTLV occurred. HTLV infection was monitored by three methods: an indirect membrane immunofluorescence assay for HTLV p19; an in situ hybridization assay for intracellular viral RNA; and electron microscopic analysis for extracellular viral particles. Two of the five infected T-cell lines have been continuously positive for HTLV for over 24 months in continuous culture. B-cell lines from the same individuals could not be infected by HTLV-I Despite the release of viral particles from the infectedc&ures detected by electron microscopy, no extracellular reverse transcriptase was found. HTLV infection stimulated increased long-term growth of the T cells although all HTLV-l(c,)-infected cultured cells always remained dependent on the addition of TCGF for growth. Phenotypic characterization of the infected cells by monoclonal antibodies, HLA typing, cytochemical and cell surface markers showed that all the infected cells were mature T cells and were easily distinguished from the cells used as a source of HTLV for infection. The infected cells were either of a predominantly helper or of a suppressor phenotype showing that both mature T-cell subsets can be infected. Whether these data indicate that there is a genetic basis for susceptibility of human T cells to HTLV infection or reflect an increased sensitivity of some cells to infection by low titers of HTLV remains to be determined. These results provide further evidence for a predominant T-cell tropism of HTLV.

Infection and transformation of fresh human umbilical cord blood cells by multiple sources of human T‐cell leukemia‐lymphoma virus (HTLV)

“…These cells express HTLV proteins, release type4 virus particles and contain surface receptors for TCGF. These results demonstrate that HTLV isolated from T-cell leukemic to numerous human and other mammalian cell lines by cell-free procedures, as well as to fresh human hematopoietic cells, including umbilical cord blood leukocytes, were negative, with the exception of expression of viral proteins in cultured T cells from close relatives of the leukemic patient (Ruscetti et al, 1983, and our personal observation). However, many other sources of HTLV can infect fresh cord blood leukocytes Miyoshi ef al., 1981b;Yamamoto et al, 1982) and as we detail here, new HTLV isolates from patients living in different parts of the world can infect and transform fresh umbilical cord blood lymphocytes.…”

Host cell range of adult t‐cell leukemia virus I. Viral infectivity and binding to various cells as detected by flow cytometry

“…The virus could only be isolated from T-lymphocytes of leukemia patients after culture in the presence of T-cell growth factor (Poiesz et al, 1980). Similarly, co-cultivation of the virus-producing cells with cord lymphocytes, or infection with cell-free virus, led to the establishment of transformed lines bearing the characteristics of mature T but not B or other cells (Chen et ul., 1983;Hoshino et al, 1983;Ruscetti et al, 1983). However, our data and other recent studies suggest that HTLV-like viruses may have a wider host range than was previously assumed.…”

Viral Aetiology of Adult T-Cell Leukaemia

“…Chosa et al (1982), on the other hand, reported that cell-free virus from MT-2 cell cultures infected and induced ATLA in the presence of phytohaemagglutinin in leukocytes from randomly selected healthy individuals without anti-ATLA antibody. Likewise, Ruscetti et al (1983) reported that PBL from members of the family of patient CR who had no anti-HTLV antibody, were infectible by cell-free virus, whereas PBL from unrelated subjects were not. It was shown by means of membrane immunofluorescence that cell-free ATLV derived from MT-2 cells was able to adsorb to many haematopoietie cell lines from various species, such as man, mouse and marmoset, thus suggesting the presence of virus receptors in a wide range of animal tissues (Yamamoto et al, 1984a).…”