The sensitivity of
alpha-naphthyl acetate esterase (
ANAE) activity of human, bovine, canine, and murine leukocytes to low (42 micrograms/ml incubation mixture) and high (1.5 mg/ml incubation mixture) concentrations of
sodium fluoride (NaF) was compared. The
ANAE activity of bovine and canine monocytes was only slightly inhibited by the low concentration of NaF, whereas that of murine peritoneal macrophages was moderately inhibited and that of human monocytes was completely inhibited. Human and canine monocytic
ANAE was completely inhibited by the high concentration of NaF, whereas the
ANAE activity in 1% of bovine monocytes and murine peritoneal macrophages was not inhibited. The
ANAE activity of human and murine lymphocytes in nonenriched venous blood samples showed no or negligible NaF sensitivity to the low concentration of NaF, whereas bovine lymphocytic
ANAE showed slight and canine lymphocytic
ANAE moderate NaF sensitivity. The
ANAE of murine T-
lymphoma L5178Y cells was resistant to the low concentration of NaF, but the
ANAE of both murine T-
lymphoma L5178Y cells and murine lymphocytes was completely inhibited by the high concentration of NaF. Human, bovine, and canine lymphocytic
ANAE showed marked NaF sensitivity toward the high concentration of NaF, showing 73%, 86%, and 93% inhibition, respectively. The neutrophils in murine venous blood and
ascites were positive for
ANAE activity, which was only slightly inhibited by the low concentration of NaF but completely inhibited by the high concentration. Results of this investigation demonstrate that the
ANAE of leukocytes of various species show remarkable differences in its sensitivity to low and high concentrations of NaF, indicating that appropriate concentrations of NaF are required for distinguishing the
ANAE of lymphocytes and monocytes of different species.