RISK-FACTORS FOR ADULT T-CELL LEUKEMIA AMONG CARRIERS OF HUMAN T-LYMPHOTROPIC VIRUS TYPE-I

The presence of circulating ''flower cells'' and a low prevalence of a ntibody to Tax regulatory protein of human T-lymphotropic virus type I (HTLV-I) are characteristics of adult T-cell leukemia (ATL). To exami ne the predictability of levels of HTLV-I antibodies and of flower cel l-like abnormal lymphocytes (Ably) for the risk of AIL among asymptoma tic HTLV-I carriers, we prospectively evaluated the levels of viral ma rkers of five HTLV-I carriers who developed ATL and 38 age-, sex-, and screen-matched HTLV-I-positive controls in the Miyazaki Cohort Study. After accounting for matching factors, Ably level was slightly, but n ot significantly, higher among cases than among controls (P = .13). An ti-HTLV-l (odds ratio [OR] = 1.6 per twofold dilution; 95% confidence interval [CI] 0.94, 3.8) was associated with ATL diagnosis, but antibo dy to Tax regulatory protein (anti-Tax) was not (OR = 0.78: 95% CI 0.2 6, 1.7). Anti-Tax level was low for all ATL cases for up to 10 years p receding their diagnosis, independent of the level of anti-HTLV-l tite r. HILV-I carriers with a higher anti-HTLV-l titer and a lower anti-Ta x reactivity may be at greatest risk of ATL. (C) 1998 by The American Society of Hematology.