Chemical reactions in cells from leukemic cats.

Cytochemical staining for leukocyte alkaline phosphatase(LAP), nonspecific esterase (NSE), nonspecific esterase with fluoride inhibition (NSE-F), periodic acid Schiff (PAS) reactivity, and peroxidase (PO) was valuable in identification of the neoplastic cell type in 10 leukemic cats. Staining both blood and bone marrow smears was often necessary for making the correct diagnosis. Cytochemical staining resulted in changing the morphologic diagnosis of leukemia in two of the 10 cats. Also, increased LAP activity, probably a marker for myelocytic leukemia in the cat, was observed in bone marrow cells from three nonleukemic, FeLV-positive cats.