Seroprevalence of HTLV-I and HTLV-II in marrow transplant recipients

HTLV-I and HTLV-II can both be transmitted through blood transfusions. Although the seroprevalence of HTLV-I/II in volunteer blood donors in low, patients with leukemia who received multiple blood transfusions are at increased risk for HTLV-I/II infection. Patients undergoing marrow transplantation for malignant and non-malignant diseases have often received multiple transfusions prior to transplantation. The seroprevalence of HTLV-I/II in marrow transplant recipients is not known, however. We studied pre-transplant sera from 317 patients receiving allogeneic or syngeneic marrow transplant in 1988 for antibodies to HTLV-I/II using an ELISA. Six sera were positive in this assay and nine other sera had absorbance values elevated above background. One of these 15 sera was confirmed positive in a Western blot assay; six others had an indeterminate reactivity. The seropositive patient was infected with HTLV-I and not HTLV-II as determined using a synthetic peptide-based ELISA; the indeterminate sera did not show reactivity to either HTLV-I or HTLV-II in this assay. Differentiation of HTLV-I from HTLV-II infection was also shown using a modified recombinant Western blot assay in which the seropositive patient showed reactivity to recombinant HTLV-I env gp46 and not recombinant HTLV-II env gp46. These results show infection with HTLV in one of 317 patients (0.3%) prior to marrow transplantation. The clinical consequences resulting from HTLV-I/II seropositivity during the severe immunosuppression accompanying marrow transplantation are not known. Testing blood donors for HTLV-I/II as is currently practised should reduce seroprevalence of HTLV-I/II in previously transfused marrow transplant recipients.