The dot-ELISA test for the detection of anti-PGL-1 IgM in leprosy patients and their contacts

Since dot-ELISA has recently been reported to be a sensitive, simple and method, we have compared it with the conventional microplate ELISA method. Sera of 124 leprosy patients, 136 household and professional contacts, and 92 controls were tested for a antibodies against a Mycobacterium leprae antigen using dot-ELISA on nitrocellulose membrane filters and microplate ELISA. The sensitive of the techniques was similar for multibacillary patients, but dot-ELISA was less sensitive for paucibacillary patients although it was more specific (100%) than ELISA (93,4%). Of 21 household contacts that gave a response by ELISA, 3 were also positive by dot-ELISA; one of these 3 developed indeterminate leprosy 12 months later and the other was diagnosed as borderline lepromatous after 28 months. These data indicate that dot-ELISA has a high spedificity and can be a useful tool in field evaluation

T-cell response to my mycobacterial antigens in lepromatous and tuberculoid leprosy

We showed that a large fraction of lepromatous patients do harbor helper-type circulating T-cells that can be activated in vitro by Mycobacterium leprae. M. leprae and PPD triggered T-cell lines could be then obtained from both tuberculoid and lepromatous patients. The proliferative response of these helper T-cells is predominantly directed against epitopes shared by several species of mycobacteria, in lepromatous patients as well as in tuberculoid patients, but species specific T-cells are also present. When presented in the context of M. leprae, these cross reactive epitopes usually fail to stimulate the T-cell lines of lepromatous patients, because of the contamination of the lines by supressor T-cells actavable by M. leprae. In one lepromatous patient, PPD and M. leprae reactive T-cell lines and clones (of the CD4 phenotype), exhibited a strong cytotoxic activity to autologous target cells coated with antigen: the relevance of this phenomenon to the pathophysiology of lepromatous leprosy remains however unknown.