Cytolytic activity against mycobacterial antigens: differences between haemophiliacs with and without HIV infection

Although asymptomatic haemophiliacs have been shown to have abnormalities of their immune response, independent of HIV, clinical evidence of significant immunosuppression is limited. The only clinical report has been an outbreak of M. tuberculosis in which a group of haemophilic boys appeared unduly susceptible to infection. These boys are now all HIV seropositive. Along with a group of HIV seronegative children with coagulation disorders and non-haemophilic HIV seropositive men, these boys have been restudied to examine immune response to PPD. The HIV seropositive haemophilic boys that had had M. tuberculosis infection had reduced cytolytic response to PPD pulsed macrophages comparable to the non-haemophilic HIV seropositive men. The HIV seronegative children with coagulation disorders showed a reduction in cytolytic activity at low effector:target ratios compared to normal controls. In vitro studies showed that exogenous factor VIII concentrate could inhibit cytolytic activity to PPD pulsed macrophages. The possible role of chronic blood-borne virus infection and factor VIII concentrates in the original outbreak are discussed.