Activation of the bactericidal capacity of blood granulocytes. Evaluation of a new method and the effect of levamisole.

In most polymorphonuclear (PMN) bactericidal assays each PMN is given appr. 0.5-4 bacteria to kill but it has not been sufficiently shown that this ratio is optimal for the detection of changes in PMN killing functions. One PMN, incubated with increasing amounts of Staph. aureus, can kill between 45 and 90 colony forming units (CFU). Therefore a new assay, giving each PMN a submaximal bacterial amount (i.e. using 2-4 CFU/PMN) concerning the effects on PMNs of thermal inactivation and of levamisole. Exposure to 46 degrees C for 3-5 minutes decreased the killing capacity, easiest descernable with the standard assay. Incubation with levamisole in concentrations ranging between 10(-6) and 10(-7) mol/l increased the PMN killing capacity, and this was most evident with the modified assay. Thus, enhancements of PMN killing functions might be detected better with the present modified PMN bacterial assay, whereas impairments are disclosed more readily with the standard assay.