Leukocyte tartrate-resistant acid phosphatase as marker for the transitionof monocyte to macrophage.

The presence of the 5 degrees isoenzyme of leukocyte tratrate-resistant aci d phosphatase (FATRE) was investigated in human peripheral blood monocytes in 32 samples: 26 normal, 4 thrombocytopenia, 1 anemia and 1 hairy cell leu kemia. The Cobe Spectra Version 4 cell separador was used for 3 samples whi le the others were obtained by centrifugation with or without latex particl es in order to study macrophages and monocytes, respectively. Using a Sigma Kit for both total acid phosphatase and FATRE reactions, the presence of t wo monocyte populations was detected, one slightly positive and the other n egative for FATRE. Upon the addition of latex particles, the monocytes were transformed into intensely FATRE positive macrophages. It can be concluded that FATRE must play an important role in macrophage function and conseque ntly in human cell immunity.