The use of antigen-bearing nitrocellulose particles derived from Western blots to study proliferative responses to 27 antigenic fractions from Mycobacterium leprae in patients and controls.

Antigens present in sonicates of Mycobacterium leprae were separated by SDS-PAGE, blotted electrophoretically on to nitrocellulose, and visualized with a colloidal gold stain. Six bands identified by existing monoclonal antibodies, and a further 21 bands not previously studied, were converted into antigen-bearing nitrocellulose particles for use in vitro lympho-proliferation studies. Controls (putative non-contacts) responded poorly to the antigenic fractions presented in this way. Contacts responded variably to a wide range of the antigens, and most frequently (23%) to the 18,000 MW fraction. Responses to this, and to several other low molecular weight antigens, were not seen in non contacts, and were very rare in all patient groups, which tended to respond to high molecular weight components. The most interesting individual band was at 36,000 MW. This caused significant stimulation of cells from 25% of tuberculoid donors, but never stimulated the cells from lepromatous cases. Indeed this fraction significantly suppressed the background proliferation of the cells from 30% of the lepromatous cases, though the significance of this observation is unclear. Responses to the 65,000 MW heat-shock protein did not differ significantly between the donor groups. Overall the results suggest that the spectrum of clinical leprosy may not be determined by the response to any one antigen. However, this study can not rule out the possibility that the response to one or a few antigens determines the outcome during the first few days after infection.