2014 Volume 60 Issue 6 Pages 592-599
HTLV-1 antibody testing has been widely used to detect HTLV-1 infection, and high proviral load (PVL) has been reported as one of the risk factors for development of ATL. In this study, we measured the titer of antibodies for HTLV-1 in infected individual using 675 samples from participants enrolled in the Joint Study on Predisposing Factors of ATL Development (JSPFAD). The anti-HTLV-1 antibody titer in particle agglutination assay (PA) rose along with PVL, indicating a correlation between antibody titer and PVL. The titer may represent an easy-to-measure biomarker for the risk of ATL development. In 49 of 604 asymptomatic HTLV-1 carriers (8.1%), PV was not observed; however, antibodies were detected. Furthermore, sequential samples for seven years from identical participants, whose PVLs were around the detectable threshold throughout the donation period, held positive on antibody tests. While all the examined ATL patients in complete remission were negative for PV detection, they continued to show clearly positive for anti-HTLV-1 antibodies. These observations suggest the existence of HTLV-1-infected individuals without appearance of PV in peripheral blood. Antibody testing, in addition to PV detection, is therefore essential for diagnosis of HTLV-1 infection.
