Selective histochemical procedure for eosinophil leukocytes.

I N THE COURSE of cunrrent investigations on leukocyte granules, the questioni arose as to w’hether the group responsible for the stable sudanophilia might be a primary amine. It is well known that primary amines are differentially destroyed by nitrous acid,’3 thus: RNH2 + HNO2-ROH + H2O + N2. In testing this hypothesis we used both Vans Slyke’s reagent* arid molar solutionis of sodium nitrite in distilled water, in normal acetic acid arid ins normal hydroehioric acid. Molar solutions of sodium nitrate ins the same solvents, arid the same solvents alone w’ere used as controls. Immersion periods of 10 minsutes, 1 hour and 6 hours were tried. After these exposures leukocyte gransules were stained by oil red 0 and by Sudan black B. As a control on the effectivensess of the nitrous acid treatment, Giemsa stains at pH 6.5 were used. Sudansophilia was riot destroyed. According to Monn#{233}arid Slautterback4 the nuclear histones of sea urchins eggs stain red by the Mallory-Heidenhains “Azan” method,5 while yolk granules stain blue. On deamination with Van Slyke’s reagent both of these tissue componiensts lose this oxyphilia. In accord with these findings it was expected that the eosinsophilia of erythrocytes and eosinophil leucocyte granules would be lost. Contrary to our expectations, eosinophil leukocyte granules still stained pink with Giemsa, even after 6 hours in Van Slyke’s reagent. The most convenient and effective procedure of those tried w’as that employing a 10 minute bath in a molar solution of sodium nitrite in normal acetic acid.