Gender difference in skin reactivity to purified protein derivative among carriers of HTLV-I in Japan

The incidence of malignancies due to oncogenic virus infections tends to be higher in men than in women. Gender-related differences in cell-mediated i mmunity, which plays a role in Viral pathogenesis, may explain this observa tion. To explore this possibility in the context of HTLV-I infection, we ex amined skin reactivity to purified protein derivative (PPD) among 128 resid ents of an HTLV-I endemic area in Japan, who were born before 1921 and are assumed to have been exposed to M. tuberculosis bacilli. The odds ratio (OR ) for reduced PPD reactivity (erythema <10 mm in diameter) was calculated b y multiple logistic regression analysis. Men were significantly less likely than women to have reduced PPD reactivity among HTLV-I-negative individual s (26% Versus 59%; p < .01); whereas this gender difference was not apparen t among HTLV-I carriers (63% versus 62%; p = .87). HTLV-I positivity was st rongly associated with reduced PPD reactivity in men, but not in women (odd s ratio [OR], 7.3 versus 1.2; p = .05). Although this observation may be du e, in part, to a longer average duration of HTLV-I infection in men compare d with women, the finding also raises the possibility that men may be inher ently more susceptible to loss of PPD reactivity by HTLV-I infection.