Effect of Mycobacterium leprae's phenolic glycolipid-I on interferon-gamma augmentation of monocyte oxidative responses.

Peripheral blood monocytes were pretreated with phenolic glycolipid-I (PGL-I), dimycocerosyl phthiocerol (DIM), or mycoside A, then cultured in the presence or absence of interferon-gamma (IFN-gamma). Their oxidative responses to Mycobacterium leprae, phorbol myristate acetate (PMA), and opsonized zymosan were evaluated. In response to M. leprae, monocytes pretreated with PGL-I released less O2- than nonlipid-treated control cells. The IFN-gamma augmentation of oxidative responses was suppressed only when in PGL-I-pretreated monocytes and only when the stimulus was M. leprae. This suggests that PGL-I, by affecting the IFN-gamma enhancement of phagocytic cell oxidative responses, aids further the intracellular survival of M. leprae.