Heiminthes & Immune Responses to Mycobacterial Antigens

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Addis Ababa University


Tuberculosis has become the major killer disease globally. As it is the case with most other infectious diseases the magnitude of the problem is the highest in resource poor countries. There are several means to control the disease. One of these is the use of vaccine (BCG). However, the vaccine offers the least protection against puhnonary tuberculosis, the most infectious fonn of the disease, in areas where TB is most prevalent. Part of the explanation for this may be that chronic infectious disease particularly, hehninthes, in these areas may polmize the immune response towards humoral type when cell mediated inununity takes the lions share in defending the body against intracellular infections. In order to assess whether intestinal helminthes could influence mycobacteria specific immunity, we investigated the ill vivo and ill vitro mycobactelia specific immune responses of helminth exposed population at Kotebe Teacher's Training College. Our finding was that dewonning significantly enhanced the ill vitro lymphocyte proliferative responses, IFN-y and IL-IO production in response to mycobacterial antigens and a T cell mitogen, PHA, compared to untreated controls. Moreover, the initially PPD non reactive subjects were BCG vaccinated and later tested for mycobacteria specific immune responses ill vivo and ill vitro. We found that BCG, when given after deworming caused significant improvement in T cell proliferation and IFN-y production compared to pre-vaccination levels in response to a mycobacterial antigen, PPD, whereas in the placebo group the difference was not significant. This finding support the notion that intestinal hehninthes may impair immune responses against mycobactelial infections and that BCG vaccination may confer better protection if given after dewonning in helminth exposed population which is an already established notion in veterinary medicine.