Chromosome studies in HTLV-I, -II, and HIV-1, -2 cell lines infected in vivo and in vitro

HTLV-I, II and HIV-1, 2 are T-cell tropic viruses, all belonging to the retrovirus family. These viruses are transmitted horizontally by intimate contact or through blood products. The study of chromosomal changes in these T cells may enhance our understanding of the nature and mechanism of these viral infections. However, because of the cytopathic effect of these viruses on T cells, the direct observation of abnormalities in these cells is sometimes difficult. We performed chromosomal analysis on six HTLV-I cell lines from patients with HTLV-I-positive leukemia/lymphoma, one HTLV-I variant cell line, and two HTLV-II-positive cell lines. The results of these studies were compared with the findings in an earlier (published) study of direct preparations and short-term cultures of cells from 11 HTLV-I-positive NIH patients. Our study also included cytogenetic analysis of seven established cell lines and six normal peripheral bloods infected in vitro with the HTLV-IIIB strain of HIV-1 (five cell lines and six bloods) or HIV-2 (two lines); all were studied both before and after viral infection. The results showed that all six HTLV-I cell lines and the variant cell line had multiple chromosomal changes: three lines had deletions of chromosome 6, with breakpoints between q21 and q25. Nine of the 11 NIH patients with HTLV-I had clonal abnormalities, and six of these nine had chromosome 6 deletions with breakpoints ranging from band q11 to band q23. The high incidence of 6q involvement may be of considerable significance in this clinical subgroup of HTLV-I patients. The two HTLV-II cell lines were established from patients suffering from HTLV-II infection. Both of these cell lines had translocations of chromosome 21 at p11, and both had extra copies of chromosome 20; no known oncogenes or receptors are located on these two chromosomes. Chromosome 17 was the chromosome most frequently involved (three lines) in the five HIV-1-infected cell lines, followed by chromosomes 3 and 21; it is of interest that NGL (also known as C-ERBB2 or NEU oncogene), CD7 (a lymphocyte antigen), HTLV-1 receptor, NGFR (nerve growth factor receptor), and MIC6 are all cell surface antigens coded by genes on chromosome 17q. No specific chromosome abnormalities were found in the normal blood samples infected with HIV-1, and no unique chromosome changes were noted in the two cell lines infected with HIV-2; however, the infected H9 line had a chromosome 17 abnormality, a translocation involving band 17p11.