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 immunity, which plays a role in viral pathogenesis, may explain this observation. To explore this possibility in the context of HTLV-I infection, we examined skin reactivity to purified protein derivative (PPD) among 128 residents 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 by multiple logistic regression analysis. Men were significantly less likely than women to have reduced PPD reactivity among HTLV-I-negative individuals (26% versus 59%; p < .01); whereas this gender difference was not apparent among HTLV-I carriers (63% versus 62%; p = .87). HTLV-I positivity was strongly associated with reduced PPD reactivity in men, but not in women (odds ratio [OR], 7.3 versus 1.2; p = .05). Although this observation may be due, in part, to a longer average duration of HTLV-I infection in men compared with women, the finding also raises the possibility that men may be inherently more susceptible to loss of PPD reactivity by HTLV-I infection.