Antibody and lymphocyte responses to Mycobacterium tuberculosis culture filtrate antigens in active and quiescent (cured) pulmonary tuberculosis.

Uma, H.; Selvaraj, P.; Reetha, A.M.; Theresa Xavier; Prabhakar, R.; Narayanan, P.R.

Indian Journal of Tuberculosis; 1999; 46; 21-28.          

Summary : Humoral and lymphocyte responses to Mycobacterium tuberculosis culture filtrate antigens were studied in active pulmonary tuberculosis (ATB) cases (n=62), inactive (cured/quiescent) tuberculosis (ITB) patients (n=62) and healthy control subjects (n=60).

      Active tuberculosis patients showed very high antibody titre to M. tuberculosis culture filtrate antigens as compared to ITB and control subjects. M. tuberculosis antigens from 17 to 80 kDa were recognized by the plasma of all ATB and ITB patients as well as control subjects. However, the 38, 32-34, 30-31 and 27 kDa antigens were recognized more by the ATB patients as compared to the control subjects while the 64/66 kDa antigen was mostly recognized by the cured patients. Increased lymphocyte responses were seen with increasing concentrations of M. tuberculosis culture filtrate antigens and mitogens such as Phytohaemagglutinin (PHA) and Concanavalin-A (Con-A) in ATB and ITB patients as well as healthy control subjects. However, a low or suppressed lymphocyte response to PHA, Con-A and M. tuberculosis culture filtrate antigens was seen in ATB patients compared to ITB patients and control subjects.

      The study suggests that during the active stage of the disease, the humoral immune response is augmented but the antigen and mitogen induced lymphocyte response (an in vitro correlate of CMI response) is suppressed. This further suggests that the humoral immune response regulates the CMI response during the active stage of the disease; when the disease is cured, the antibody response declines and the lymphocyte response to antigens and mitogens increases to the same level as found in controls. This suggests that normal immune status gets restored in cured patients.

Keywords : Antibody response; Antigen recognition; Lymphocyte response; M. tuberculosis antigens; Mitogens; Pulmonary tuberculosis.

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