LONGITUDINAL TRENDS IN SERUM LEVELS OF MYCOBACTERIAL SECRETORY (30 KD) AND CYTOPLASMIC (65 KD) ANTIGENS DURING CHEMOTHERAPY OF PULMONARY TUBERCULOSIS PATIENTS

Antigen 85 (mol. wt 30000) (30 kD), secreted by actively growing mycob acteria under axenic conditions, and mel. wt 65000 (65 kD), a cytoplas mic antigen released during mycobacterial lysis, were used to monitor the efficacy of chemotherapy in previously untreated pulmonary tubercu losis (UPTB) patients using enzyme-linked immunosorbent assay. Sera fr om 125 UPTB patients were examined for each of the 2 antigens individu ally and for the ratio of secretory (30 kD) to cytoplasmic (65 kD) ant igen (SCR), before commencement of treatment, after intensive phase (I P), completion of optimum period of treatment (COPT) and 6 months post -COPT. 116 controls (normals and contacts) were also checked for these antigens. The detection of 30 kD and 65 kD antigens in UPTB patients had a sensitivity ranging from 50-57% (mean 30 kD value: 0.64 +/- 1.24 ngs/ml) to 20-22% (mean 65 kD value: 0.51 +/- 1.87 ngs/ml), respectiv ely, whereas in controls it ranged from 2-8% (0.05 +/- 0.28 ngs/ml) to 14-47% (0.09 +/- 0.22 ngs/ml), respectively. Although the decline in 30 kD positivity was more evident at COPT, computation of the SCR deno ted efficacy of chemotherapy more readily at LP. Similarly, SCR resolv ed the ambiguity between individual antigen levels and the clinical st atus of a patient. Since significant numbers of patients demonstrated 30 kD at IP it may be computed that the lifespan of circulating 30 kD in serum could be at least 2 months after the start of treatment, decl ining gradually thereafter. Although seromonitoring for secretory anti gen generally reflects the efficacy of chemotherapy, the interpretatio n of findings clearly requires further elucidation.