Immunological defect in leprosy patients: altered T-lymphocyte signals

The early events of activation were studied in paucibacillary (TT/BT) and m ultibacillary (BL/LL) leprosy patients by stimulation of their lymphocytes with mitogenic agents (calcium ionophore A23187/PMA) and Micobacterium lepr ae antigen (PGL-1). Maximum proliferation in response to PMA/A23187 and PGL -1 was observed in the BT/TT patients and the control group, respectively. Inositol triphosphate (IP3) and calcium were constitutively elevated in BT/ TT and LL/BL patients. PMA/A23187 caused an increase in both IP3 and [Ca2+] (i) in BT/TT patients and controls. PGL-1 marginally increased IP3 levels i n BT/TT patients. In the LL/BL patients, although PMA/A23187 increased IP3 levels: but no change was seen in [Ca2+](i), PGL-1 had no effect. Protein k inase C levels were seen to be associated with particulate fractions in BT/ TT patients and were found to increase further in response to PMA/A23187. P GL-1 did not increase translocation of protein kinase C in controls or LL/B L patients. A preactivated and sensitised slate of T-lymphocytes was observ ed in BT/TT patients, responsive to antigen and mitogens, whereas the cells of LL/BL patients were unresponsive to PGL-1. The altered signal transduct ion events characterised in the MB patients thus correlate well with the an ergic state of their cells. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.