Cytochemical Observations on Chicken Monocytes Macrophages and Giant Cells in Tissue Culture

Cultures of leukocytes from chicken blood grown in fluid medium in roller flasks were stained for lipids, carbohydrates, phosphatase, esterase, and succinic dehydrogenase in order to study the cytochemical changes associated with the transformation of monocytes to macrophages, epithelioid cells and multinucleate giant cells. The great variability in cell form observed by previous investigators in such cultures was confirmed. The cells were usually round but not uncommonly were stellate or fusiform, sometimes bearing a striking similarity to fibroblasts, at other times resembling sheets of mesothelium. The factors determining their size and shape were obscure, but low pH seemed to favor the formation of giant cells. Monocytes of chicken blood were ordinarily devoid of stainable lipid, carbohydrate and enzymes. Macrophages and epithelioid cells which developed from them were negative for esterase, succinic dehydrogenase and alkaline phosphatase but gave a strong reaction for acid phosphatase, localized in their enlarged centrosphere or Golgi zone. This region also contained a saliva-resistant, periodic acid-Schiff positive material, probably a carbohydrate-protein complex and its relation to the enzyme acid phosphatase has been considered. Numerous small lipid droplets were disposed around the periphery of the Golgi zone. Giant cells occasionally contained glycogen. The acquisition of acid phosphatase by monocytes during their transformation to macrophages appeared to be related to their enhanced phagocytic activity.