Polymorphonuclear activation in leprosy. I. Spontaneous and endotoxin-stimulated reduction of nitroblue tetrazolium: effects of serum and plasma on endotoxin-induced activation.

Spontaneous nitroblue tetrazolium (NBT) reduction was evaluated in neutrophils from patients with the different types and forms of leprosy, and compared with reduction obtained form cells from normal controls. Leucocytes from the same subjects were stimulated in vitro by endotoxin, and the rise in percentage of cells reducing NBT was determined. Patients of all groups, with the exception of those with reactional lepromatous leprosy (RLL) had an essentially normal proportion of reducing cells. Neutrophils were normally activated by endotoxin. This indicates that while Mycobacterium leprae does not by itself stimulate leucocytes from leprosy patients, there is no overall anergy of neutrophils in lepromatous or other forms of leprosy. In RLL the proportion of reducing cells was significantly raised. Stimulation with endotoxin was able further to enhance this proportion, but not above levels reached by stimulation of normal cells. Neutrophil activation could not be reproduced by mixing serum from highly activated RLL patients with normal leucocytes. An inhibitory effect of serum and plasma over in vitro endotoxin activation of neutrophils was found.