Semi-quantitative detection of Mycobacterium leprae antigens in skin scrapings: suitability as a laboratory aid for field diagnosis of leprosy.
We describe here a method, potentially suitable for field applications, for semi-quantitative detection of Mycobacterium leprae antigens in skin scrapings, which are taken normally for smear microscopy. Thirty acid-fast bacilli-negative paucibacillary (PB) leprosy patients comprised the main study group; eight acid-fast bacilli-positive multibacillary (MB) patients and five healthy laboratory workers served as controls. Samples in saline were spotted on nitrocellulose paper and probed with mycobacterium-specific polyclonal or M. leprae-specific mAbs against 12, 35 and 65kDa protein antigens, using a dot-ELISA format. Spot densities were read through a densitometer and also graded visually. The polyclonal antibody produced the best sensitivity, resulting in densitometric detection of mycobacterial antigen in 100% MB, 76% multiple-lesion PB and 62% single-lesion PB patients. None of the healthy volunteers showed antigen positivity. A correlation was noted between the densitometric and visual estimates of the antigen. Determination of antigen in the lesion and an apparently uninvolved area of skin in a subset of PB patients provided clues to the state of the underlying infection. Serological positivity of PB patients for M. leprae-specific antibodies against the 35kDa and phenolic glycolipid-I antigens was too low (<20%) for any diagnostic significance.
Chaturvedi
Vinita
V
Anti-TB Screening Unit, Central Drug Research Institute, P.O. Box 173, Lucknow 226001, India.
Girdhar
Bhawneshwar K
BK
Sengupta
Utpal
U
Sinha
Sudhir
S
D000907:Antibodies, Bacterial / Q000276:immunology*; D000942:Antigens, Bacterial / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D007918:Leprosy / Q000175:diagnosis*; D009166:Mycobacterium leprae / Q000276:immunology* / Q000302:isolation & purification; D012680:Sensitivity and Specificity; D012867:Skin / Q000382:microbiology*; D017192:Skin Diseases, Bacterial / Q000382:microbiology*
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial