Detection of S-100 protein and anticeramide antibodies in leprosy patients by ELISA

The status of assay for S-100 antigen protein and anticeramide antibodies in serum in understanding nerve damage in different forms of leprosy were evaluated by the enzyme immunoassay. Based on the clinical and smear examination, patients were classified as indeterminate (Ind), tuberculoid (TT), borderline tuberculoid (BT), borderline lepromatous (BL) and lepromatous (LL). Antibody levels against ceramide were observed in sera of leprosy patients with 37.5% of Ind, 28% of TT, 66% BT, 78% BL and 62% LL patients positive as against 8% endemic normal sera. The mean OD ranged from 0.141 to 0.275 in different groups of leprosy. In contrast, S-100 was detected in 71.4% Ind, 88.8% TT, 76.4% BT, 100% BL and 95.8% LL, while 5% of ENL samples were positive for S-100 antigen. Mean S-100 levels in these different categories of patients were significantly higher Ind--0.45 ng/ml, TT--0.32 ng/ml, BT--0.23 ng/ml, BL--0.23 ng/ml, LL--0.19 ng/ml as compared to that of normal 0.07 ng/ml. In general S-100 seems to be a more sensitive and reliable marker than anticeramide antibodies for nerve damage. Five out of 7 indeterminate cases show increased levels of S-100, showing an extent of nerve damage similar to that of TT and could be a useful marker for assessing nerve damage in indeterminate patients for better management.