Human tuberculosis sera show prominent antibody responses to particulate fractions of Mycobacterium tuberculosis.

Sera from smear-positive pulmonary tuberculosis patients and normal control subjects in Madras were analyzed by Western blotting for their reactivity with soluble and particulate (membrane-rich and cell wall-rich) antigen fractions extracted by sonication from Mycobacterium tuberculosis H37Rv. Discrimination between patient and control sera was best with particulate antigen fractions: 60% of patient sera reacted with a 38-kD antigen band and 90% reacted with a 55-kD band. Reactions of control sera with the 38- and 55-kD bands were infrequent and faint. The results suggest that a serodiagnostic test might be based on quantitation of responses to these two antigens.