Serum anti-lipid antibodies in patients affected by leprosy in a high-burden municipality in Brazil: a cross-sectional study.

Early diagnosis plays a pivotal role in breaking the epidemiological chain of Mycobacterium leprae transmission. Currently, diagnosis relies on clinical, dermato-neurological features, and histological/microbiological assessments. This prospective cross-sectional study investigated whether IgA, IgM, and IgG anti-lipid antibodies can be used to improve the diagnostic performance for leprosy-affected patients in a high-burden municipality in Brazil. Serum samples from 91 volunteers, including patients with leprosy (n=62), household contacts (n=21), and endemic controls (n=8) were screened by enzyme-linked immunosorbent assays (ELISA) for IgA, IgM, and total IgG against four lipids-namely, cardiolipin (CL), phosphatidylcholine (PTC), phosphatidylethanolamine (PE), and phosphatidylinositol (PI)-and a glycosphingolipid-sulfatide (SL)-found in the bacterial cell wall. Antibodies against all lipids were detected in the sera of patients with leprosy. Significantly higher levels of IgA anti-CL, anti-PE, and anti-PTC, IgM anti-CL, and total IgG anti-PTC were observed in these patients compared to household contacts and endemic controls (p < 0.0001). ROC curve analyses demonstrated high accuracy in discriminating patients with leprosy from the contacts, with moderate to high sensitivity and specificity, even in paucibacillary patients. Despite the small study population and the absence of patients with other dermatological lesions for differential diagnosis, these findings suggest the potential of anti-lipid antibodies as biomarkers for leprosy detection. This approach offers a promising method to improve early diagnosis in high-burden areas, such as the studied municipality in Brazil.