Open AccessCellular and humoral immune responses to recombinant 65‐kD antigen of Mycobacterium leprae in leprosy patients and healthy controls
Author(s) -
ILANGUMARAN S.,
NARAYAN N. P. SHANKER,
RAMU G.,
MUTHUKKARUPPAN VR.
Publication year - 1994
Publication title -
clinical & experimental immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.329
H-Index - 135
eISSN - 1365-2249
pISSN - 0009-9104
DOI - 10.1111/j.1365-2249.1994.tb06234.x
Subject(s) - mycobacterium leprae , immunology , antigen , tuberculoid leprosy , immune system , lepromatous leprosy , antibody , leprosy , population , lymphoproliferative response , immunogen , peripheral blood mononuclear cell , biology , medicine , in vitro , monoclonal antibody , biochemistry , environmental health
SUMMARY Cellular and humoral immune responses to recombinant 65‐kD antigen of Mycobacterium leprae (rML65) were studied in leprosy patients and healthy contacts from a leprosy‐endemic population. Peripheral blood mononuclear cells from a considerable proportion of tuberculoid leprosy patients, healthy contacts and non‐contacts showed proliferative response to rML65 in vitro . A strong positive correlation was observed between the responses to rML65 and bacille Calmette‐Guérin (BCG) or leprosin A. Addition of recombinant IL‐2 (rIL‐2) enhanced the proportion of responders to rML65 considerably in all groups of leprosy patients, healthy contacts and non‐contacts. Among lepromatous patients this enhancement was more pronounced in the bacterial index (BI)‐negative group. These results indicate that the 65‐kD antigen of Myco. leprae is a dominant T cell immunogen in our study population. Though lepromatous patients showed poor lymphoproliferative response to rML65, their IgG antibody levels to the same antigen were markedly high. Most of the BI‐positive lepromatous patients with elevated anti‐rML65 IgG levels did not show T cell reactivity even with the addition of rIL‐2. On the other hand, tuberculoid leprosy patients, healthy contacts and non‐contacts showed good T cell reactivity but low levels of IgG antibodies to rML65, thus indicating the presence of an inverse relationship between cell‐mediated and humoral immune responses to a defined protein antigen of Myco. leprae in humans. A significant proportion of individuals among tuberculoid leprosy patients, healthy contacts and non‐contacts showed neither T cell reactivity nor elevated levels of IgG antibody to rML65. However, in most of these subjects, a T cell response to rML65 was demonstrable with the addition of rIL‐2. These results are discussed with reference to the immunoregulatory mechanisms occurring during Myco. leprae infection on the basis of differential activation of Th1 and Th2 subsets.