CELLULAR TROPISM OF HUMAN T-CELL LEUKEMIA-VIRUS TYPE-II IS ENLARGED TO B-LYMPHOCYTES IN PATIENTS WITH HIGH PROVIRAL LOAD

To establish the in vivo cellular tropism of human T-cell leukemia vir us type II (HTLV-II) in peripheral blood, subpopulations of mononuclea r cells isolated from patients with a history of drug abuse and with h igh proviral load were analyzed by polymerase chain reaction for the p resence of the proviral sequences. After purification of cellular subs ets by immunomagnetic fractionation of blood cells of an infected pati ent, HTLV-II DNA was detected in CD4(+) and CD8(+) T-cells as well as in CD19(+) B-cells. A positive PCR signal was obtained for purified B- cells also at limiting dilutions. This observation was confirmed by pu rifying the B-cell fraction by a two-step immunomagnetic procedure fro m the peripheral blood of another patient with very high HTLV-II copy number and quantifying the B-cell proviral load by means of competitiv e PCR. A proviral copy number of 90/100 B-cells was found, demonstrati ng that the great majority of these cells were infected by HTLV-II in this subject. The results indicate that HTLV-II has a broad host range in some infected individuals, showing an enlargement of cellular trop ism to a lymphocytes and suggesting that this expansion is associated with an increase in proviral load. (C) 1995 Academic Press, Inc.