EVALUATION OF CHEMILUMINESCENCE, PROCOAGULANT ACTIVITY AND ANTIGEN PRESENTATION BY MONOCYTES FROM LEPROMATOUS LEPROSY PATIENTS WITH OR WITHOUT REACTIONAL EPISODES

In this study, we evaluated the activity of peripheral blood mononucle ar cells (PBMC), isolated from treated and untreated lepromatous lepro sy patients, from lepromatous leprosy patients during and after reacti onal episodes (erythema nodosum leprosum (ENL) and reversal reaction ( RR)), and from normal healthy individuals. We determined reactive oxyg en intermediate (ROI) production, procoagulant activity (PCA) and HLA- DR antigen expression of monocytes, besides lymphoproliferation, both in the presence and absence of various stimulatory agents. Phorbol myr istate acetate (PMA) stimulated ROI production by monocytes from all t he groups studied, with patients during reactional episodes (ENL and R R) showing a significantly higher response (p < 0.009 and p < 0.00001) . Irradiated Mycobacterium leprae, although having little effect when added alone, strongly suppressed PMA-stimulated ROI production. Muramy l dipeptide (MDP) had no influence on either basal or on PMA-induced R OI production. Basal monocyte PCA, as well as M. leprae or concanavali n A (ConA)-induced monocyte PCA, was comparable in monocytes from all the groups studied. ConA was able to induce mitogenic activity in mono nuclear cells isolated from all the groups studied. M. leprae, althoug h stimulatory for normal individuals, did not induce lymphoproliferati on in lepromatous leprosy patients, except for cells from patients dur ing RR, which responded equally to M. leprae and to ConA. The absence of M. leprae-induced lymphoproliferation in lepromatous leprosy patien ts is not caused by the lack of basal HLA-DR expression, as PBMC from all individuals studied showed the same level of this antigen. Our res ults suggest an increase of spontaneous or PMA-induced monocyte activi ty, as detected by ROI production, during the reactional episode; addi tion of M. leprae suppressed this response. The increase in monocyte a ctivity could be correlated with the increase of lymphoproliferation r esponse to M. leprae during RR, but not during ENL. The importance of a possible immune suppressive action of M. leprae is discussed.