Recognition of phenolic glycolipid-I (Mycobacterium leprae) and sulfolipid-I (M. tuberculosis) by serum from Mexican patients with leprosy or tuberculosis.

SETTING: Differential diagnosis of leprosy and tuberculosis in regions where both illnesses are endemic is a prerequisite for proper identification and treatment.

OBJECTIVE: To evaluate the recognition of phenolic glycolipid-I (PGL-I) of Mycobacterium leprae and sulfolipid-I (SL-I) of M. tuberculosis by serum from patients with leprosy (LL) or pulmonary tuberculosis (PTB).

DESIGN: Purified PGL-I and SL-I were used as antigens in an ELISA test set up to assess recognition of these lipids by serum from 43 LL patients, 44 PTB patients and 38 healthy individuals.

RESULTS: Leprosy patients gave higher IgM than IgG responses to PGL-I and had comparable IgM and IgG responses to SL-I. A similar situation was observed with PTB serum. Some healthy individuals were found to contain significant levels of antibodies to both lipids.

CONCLUSION: There is no specific recognition of either of the two lipid antigens tested by serum from both leprosy and tuberculosis patients; this rules out the possibility of using PGL-I and SL-I as tools for the differential diagnosis of these two mycobacterial diseases.