Evidence for the aetiological role of blood-borne virus infections in causing reduced lectin-induced T-cell proliferation in haemophilic boys.

T-lymphocyte function, as expressed by polyclonal proliferation to lectin mitogens phytohaemagglutinin and concanavalin A, has been studied in a normal control population and three groups of haemophilic boys: group 1, HIV and HCV seronegative and treated only with a single heat-treated factor VIII (FVIII) concentrate; group 2, HIV seronegative but HCV seropositive; group 3, all HIV and HCV seropositive. Groups 2 and 3 have been previously treated with unheated and heated FVIII concentrate. Group 1 boys (HIV/HCV uninfected) showed no significant reduction in lymphocyte proliferation when compared with a control population. Group 2 and 3 boys showed an impaired response to these mitogens compared to group 1 boys and the control group. There was no relationship between FVIII concentrate received and proliferative response. The absence of immune modulation in haemophilic boys who have not acquired HIV and HCV infection implicates chronic blood-borne virus infections as the major contributory factors to impaired lymphocyte proliferative responses seen in haemophiliacs treated with large-pool concentrates. The presence of virus infections, such as HCV, may account for similar lymphocyte function abnormalities observed in previously described cohorts.