Helminths and Immunity against Tuberculosis

Sammanfattning: The efficacy of Bacille Calmette Gueri n (BCG) is low and incidence of tuberculosis (TB) is high in those areas where helminths are endemic. Protection against tuberculosis requires strong cell mediated immunity while chronic helminth infections induce responses characterized by dominant Th2 responses as well as up-regulated regulatory T cell activity. Such immunomodulation caused by helminths were shown to result in hyporesponsiveness against unrelated antigens. We hypothesized that chronic helminth infection could affect the ability of the host to control mycobacterial infections andlor the efficacy of vaccination against TB. This thesis is based on five separate clinical and experimental studies. The first was aimed to assess whether intestinal helminth infections could affect TB specific cellular responses in individuals with prior mycobacterial exposure as well as to investigate the impact of worms on the immunogenicity of BCG vaccination in humans. The result indicates that treatment of intestinal worms results in significant improvement in mycobaterial antigen induced Tcell proliferation and IFN-