[HTLV-I carriers in ATL/L-nonendemic area--with reference to blood transfusions].

: Sera from 5,705 persons were tested for antibodies to human T-cell leukemia virus type 1 (HTLV-I) by gelatin particle agglutination test (PA) and enzyme immunoassay (EIA) as screening methods, and the antibodies were confirmed by indirect immunofluorescence assay (IF) and Western blotting method (WB). The antibodies were detected in 30 (1.34%) of 2,239 patients who had received blood transfusions, 3 (0.29%) of 1,022 healthy blood donors, all 18 adult T-cell leukemia/lymphoma (ATL/L) patients, 23 (47%) of 49 family members of the ATL/L patients and 10 (0.53%) of the other 1,898 persons. Before the introduction of the mass screening of healthy blood donors by the Japan Red Cross Blood Center, 17 (2.29%) of 743 recipients tested were positive for the antibodies by PA and most of them were confirmed by IF and WB. Ten of these 17 recipients tested were negative for the antibodies before the blood transfusions. After the introduction of mass screening, 13 (0.87%) of 1,496 recipients tested were positive for the antibodies by PA, but the seroconversion of the antibodies by blood transfusions could not be confirmed clearly. In persons with low titers (1:16-1:64) in PA, the coincident rate of positive reaction with EIA, IF and WB was only 9.5%, 0.0% and 23.8%, respectively, and most of the immunoglobulin (Ig) class was IgM. On the other hand, in those with titers of 1:128 or greater in PA, the coincident rate was 72.7%, 81.8% and 90.9%, respectively, and the Ig class was IgG or IgG + IgM.