Accessory cell heterogeneity in lepromatous leprosy; dendritic cells and not monocytes support T cell responses.
Dendritic cell (DC)-enriched cell populations from anergic lepromatous leprosy (LL) patients were found to be several-hundred-fold more efficient than monocytes (MO) in promoting antigen-induced T cell responses in autologous accessory + T cell cultures. Whereas, the use of autologous monocytes over a wide concentration range failed to stimulate Mycobacterium leprae-induced T cell proliferation, DC at concentrations as low as 0.1% induced significant proliferation in 9/15 and interferon gamma production in 14/15 LL patients. Four of the LL patients who failed to show proliferation were, however, able to secrete interferon gamma in the same T cell + DC co-cultures. DC were able to present particulate leprae antigens to autologous T cells. This preference for DC as an accessory cell was not shown when the cross-reacting antigen PPD was used in parallel co-cultures. Though tuberculoid leprosy patients showed some improvement in T cell proliferation with DC as compared to MO constituted co-cultures, this was not statistically significant. These results suggest that there is a heterogeneity in accessory cell requirement across the leprosy spectrum and that many lepromatous patients possess M. leprae-reactive functional T cells.
Mittal
A
A
Biotechnology Department, All India Institute of Medical Sciences, New Delhi, India.
Mishra
R S
RS
Nath
I
I
D000942:Antigens, Bacterial / Q000276:immunology; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D015440:Leprosy, Lepromatous / Q000276:immunology*; D008213:Lymphocyte Activation; D009000:Monocytes / Q000276:immunology*; D009166:Mycobacterium leprae / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
D000942:Antigens, Bacterial; D007371:Interferon-gamma