Immunopathological Stain of Lipoarabinomannan-B(LAM-B) for Diagnosis of Leprosy

We developed an immunopathological staining of LAM-B antigen in formalin-fixed paraffin-embedded tissues, and compared it with, PGL-I immunostain-ing, Fite Faraco's stain and periodic acid carbol pararosaniline (PACPR) stain. Out of the total 28 leprosy cases, 27 were positive to LAM-B immunos-taining while 23 were positive to PGL-I stain. Fite's stain was positive in 21 cases while PACPR stain was positive in 24 cases. In scrofuloderma, LAM-Bantigen was observed only in the granuloma while no other positive findings were noted with other stains. Normal skin did not give any positivefindings with any of the stains. Other dermatoses showed no positive findings to any of the stains tested. LAM-B staining was observed in the nerveeven in the absence of bacilli in leprosy tissues. Presence of LAM-B in the cutaneous nerves is helpful in discriminating leprosy from other ycobacterioses. Considering the high sensitivity of LAM-B and the predilection of M. leprae for the nerves, we concluded that LAM-B staining can be auseful new tool in the prompt diagnosis of leprosy, especially in suspected or early cases.