Effects of cytochalasin B and dibutyryl cyclic AMP on intraleukocytic bactericidal activity.

Cytochalasin B (CB) is known to regulate the movement of intracellular microfilaments system. In this experiment, the effect of CB on the intraleukocytic bactericidal activity was first studied and concluded that CB inhibited the intracellular bactericidal activity remarkably. Addition of CB resulted in increased nitroblue tetrazolium (NBT)-dye reduction, while the specific activities of glucose-6-phosphate dehydrogenase (G-6-PD) and reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase of CB-treated neutrophils exhibited within the normal range. But the uptake of Glucose-1-14C or -6-14C was markedly inhibited by CB treatment. However, the following substances inhibited NBT-dye reduction in decreasing order: cyclic adenosine 3', 5'-monophosphate (cAMP), N6-O2' dibutyryl cyclic adenosine 3', 5'-monophosphate (DBcAMP), prostaglandin F2alpha (PGF2alpha) and prostaglandin E1 (PGE1). These drugs also decreased hexose monophosphate shunt (HMS) enzyme activities. Addition of CB and DBcAMP decreased the intracellular bactericidal activity of neutrophils. But CB had no effect on intracellular levels of cAMP. From the results obtained, it is likely that intracellular bactericidal phenomena of human neutrophils are controlled by cyclic AMP cascades and by the microfilaments system, separately.