INFLUENCE OF HLA-DR2 PHENOTYPE ON HUMORAL IMMUNITY AND LYMPHOCYTE-RESPONSE TO MYCOBACTERIUM-TUBERCULOSIS CULTURE FILTRATE ANTIGENS IN PULMONARY TUBERCULOSIS

Association of HLA-DR2 genes/gene products has been shown with pulmona ry tuberculosis (PTB) patients in India. In the present study, the inf luence of HLA-DR2 and non-DR2 genes/gene products on immunity to tuber culosis has been studied. Plasma samples of -DR2 positive patients (ac tive and inactive TB) showed a higher antibody titre to Mycobacterium tuberculosis culture filtrate antigens than non-DR2 (-DR2 negative) pa tients. Immunoblot analysis revealed a trend towards an increased perc entage of DR2 positive patients recognizing 38, 32/34 and 30/31 kDa an tigens of M. tuberculosis than DR2 negative patients. A low spontaneou s lymphoproliferative response (without antigen stimulation) was seen in HLA-DR2 positive active TB patients than HLA-DR2, negative patients . However, the antigen stimulated lymphocyte response was higher in th e -DR2 positive patients (active and inactive TB) when compared to. no n-DR2 patients. Further, an inversional correlation between antibody t itre and spontaneous as well as antigen induced lymphocyte response (m easured by H-3 thymidine uptake and expressed as counts per minute) wa s seen in HLA-DR2 positive active PTB patients than non-DR2 patients. The present study suggests that HLA-DR2 genes/gene products may be ass ociated with a regulatory role in the mechanism of disease susceptibil ity to tuberculosis. The genes white augmenting the humoral immune res ponse, they suppress the spontaneous and antigen induced lymphocyte re sponse in -DR2 positive patients with active disease.