Characterization of Haemophilus ducreyi-specific T-cell lines from lesionsof experimentally infected human subjects

Haemophilus ducreyi is the etiologic agent of chancroid, a sexually transmi tted genital ulcer disease that facilitates the transmission of human immun odeficiency virus. In the human model of infection, the histopathology of i nfected sites in part resembles a delayed-type hypersensitivity (DTH) respo nse. In this study, T cells were isolated from skin biopsy specimens obtain ed from 24 subjects who were infected for 7 to 14 days. One clone and 12 li nes that responded to H. ducreyi antigens were obtained from 12 of the subj ects. Fluorescence-activated cell sorter analysis showed that the antigen-r esponsive lines and clone were predominantly CD3(+) and CD4(+), The lines a nd clone responded to H. ducreyi antigen in a dose-dependent manner and pro duced gamma interferon (IFN-gamma) alone or IFN-gamma and interleukin-10 (I L-10) but no IL-4 or IL-5 in response to H. ducreyi, Proliferation of T cel ls was dependent on the presence of autologous antigen-presenting cells. Th e lines showed little response to antigens prepared from other members of t he Pasteurellaceae and responded to different fractions of H, ducreyi separ ated by preparative sodium dodecyl sulfate-polyacrylamide gel electrophores is. We conclude that T cells that recognize H, ducreyi antigens are recruit ed to sites experimentally infected with the organism. The lack of cross-re activity to the Pasteurellaceae and the response of the lines to different antigen fractions suggest that subjects are sensitized to H. ducreyi during the course of infection.