Identification of an immunostimulating protein from Mycobacterium leprae

Abstract

Despite the recent identification of a number of Mycobacterium leprae proteins, the major immunogenic determinants of this organism remain obscure. We isolated from M. leprae a potent immunostimulatory preparation, designated the MLP fraction, which contains a major protein of 35 kilodaltons (kDa). This protein was precipitated by monoclonal antibody ML03-A,, which recognizes a 35-kDa protein of M. leprae, and by sera obtained from patients with lepromatous leprosy. Neither sera from healthy controls nor sera from patients with pulmonary tuberculosis recognized the 35-kDa protein, and only one of four serum samples from patients with borderline tuberculoid leprosy reacted with this protein. The MLP fraction stimulated T-cell proliferation in patients with leprosy whose T cells proliferate in response to whole M. leprae cells. Apparently, the T-cell epitope associated with MLP is also expressed on M. tuberculosis and M. bovis BCG, since patients with pulmonary tuberculosis and BCG-vaccinated individuals demonstrated significant responses to the MLP fraction. The 35-kDa M. leprae protein, purified to homogeneity in the laboratory of P. J. Brennan, stimulated T-cell proliferative responses in all MLP-responsive subjects. These findings suggest that the 35-kDa protein present in MLP is an immunostimulatory component of M. leprae. In addition to serving as a useful probe for study of the T-cell anergy associated with lepromatous disease, this protein may ultimately be useful as a component of a vaccine designed to provide protection against infection with M. leprae. * Corresponding author. MATERIALS AND METHODSPatients. Heparinized blood was obtained from 11 patients with LL and 12 patients with borderline tuberculoid leprosy (BTL). The disease stage was classified by T. H. Rea of the Division of Dermatology, University of Southern California, as described by Ridley and Jopling (32). These patients were under treatment with dapsone or a combination of dapsone, rifampin, and clofazimine. None were receiving corticosteroids or thalidomide or had erythema nodosum leprosum when blood samples were taken. All of these patients had been previously studied for the ability of their T cells to proliferate in response to M. leprae in vitro (Mohagheghpour et al., unpublished data). Five of the patients with LL were included in this study because their T-cell responses to M. leprae were normal while the remaining patients with LL were nonresponders to M. leprae. Blood samples were also obtained from 7 patients with pulmonary tuberculosis (PT) from the Curicica Sanitarium, Rio de Janeiro, Brazil; 10 healthy volunteers who had received M. bovis BCG vaccinations; and 8 healthy individuals who had not been vaccinated with BCG.Antigens. Armadillo-derived whole M. leprae cells, lyophilized uninfected armadillo liver, and a 35-kDa M. Ieprae protein purified to homogeneity (single silver-stained band by sodium dodecyl sulfate [SDS]-polyacrylamide gel electrophoresis [PAGE]) were kindly provided by Collins. Recombinant M. leprae proteins ...

Effective vaccination of mice against leprosy bacilli with subunits of Mycobacterium leprae

“…Our approach has been to isolate the M. leprae components and assess their abilities to be recognized by lymphocytes of responsive patients with leprosy and confer protection against infection with leprosy bacilli in mice. Using a number of extraction procedures, we have isolated strong T-cell immunogens from M. leprae (20,21). In the present study, we demonstrated that immunization with cell wall-associated proteins of M. leprae (CWIF, (Fig.…”

“…An analysis of the precursor frequency of antigen-reactive human peripheral T cells suggests that as many were sensitive to the M. leprae cell wall protein peptidoglycan complex as to M. leprae itself (20). Independently, Mohagheghpour et al (21) have partially purified a 35-kilodalton protein from the pelleted fraction of sonicated M. leprae. This preparation, the M. leprae protein fraction designated MLP, not only reacts with circulating antibodies from patients with leprosy but, more importantly, elicits in vitro T-lymphocyte responses from patients with leprosy that parallel their responses to whole M. leprae cells.…”

Isolation of Brucella abortus ssb and uvrA genes from a genomic library by use of lymphocytes as probes

“…Though T lymphocytes play a major role in protection against facultative intracellular bacteria, antigens relevant to the humoral immune response have been studied more extensively than T-cell antigens because antigens recognized by antibodies are more technically amenable to study (40). To identify antigens recognized by T lymphocytes, complex protein preparations from intracellular bacteria have been used to investigate the cellular immune response (12,18,37). However, isolation of individual stimulatory components in complex mixtures is still difficult.…”

Advances in leprosy immunology and the field application: A gap to bridge

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