RESUMO
HLA class I antigen profile was studied in 153 unrelated patients with pulmonary tuberculosis (PTB), 40 family contacts and 289 healthy individuals by the NIH microlymphocytotoxicity test to find out the role of HLA-A, -B, -C alleles in influencing susceptibility to PTB and its various clinical groups. HLA-A2 was found to be significantly increased in the total patient group as compared to controls (38.6% vs 26.3%, p < 0.01, RR = 1.76). The increase of HLA-A2 was more pronounced in the sputum negative patients (59.4%, pc < 0.001, RR = 4.1) suggesting its possible role in the mediation of CD8+ suppressor T cell activity against Mycobacterium tuberculosis, resulting in the development of limited disease in these patients. Further, HLA-B18 was found to be decreased in patients as compared to controls (2.6% vs 7.3%, p < 0.05, RR = 0.34). None of the class I antigens was associated with the dynamics of chemotherapy or disease severity as assessed by the extent of lung involvement on chest X-ray examination.