Human Helper T Cell Lines Established by Coculture of Normal Human Cord Leukocytes with an HTLV-Il-infected Rabbit Leukocyte Cell Line (Ra-IIA)

Three helper T cell lines, designated CR -IIA (CR-IIA-1, CR-IIA- 2, and CR-IIA-3), were established by coculturing nor mal human cord leukocytes with a lethally irradiated HTLV II (human T lymphotropic virus type II)- infected rabbit leukocyte cell line (Ra-IIA). CR IIA had a normal human karyotype and expressed the surface markers CD3(+), CD4(+), CD8(-), CD19(-), CD25(+) and HLA- DR(+), confirming their helper T cell nature. CR- IIA cells were all free of Epstein- Barr virus nuclear antigen and were im-muno reactive with serum samples from HTLV- I- or HTLV-Il- infected patients and with anti HTLV- I, p19 or p24 anti body. The provirus genome of HTLV-II was detected in these cell lines by the polymerase chain reaction combined with a digoxigenin- enzyme- linked immunosorbent assay. Electron microscopy of CR-IIA-1 cells revealed a few im mature type C virus particles. These results suggest that HTLV- II was transmitted from the infected rabbit leukocyte cell line to human cord helper T lymphocytes with the development of immortalized HTLV - II- producing T cell lines. Acta Pathol Jpn 42: 347–352, 1992.