The influence of fixation and composition of incubating medium on alpha-naphthyl acetate esterase staining of T-lymphocytes and monocytes in human peripheral blood.

alpha-Naphthyl acetate esterase methods using hexazonium pararosaniline as coupler for demonstrating T-cells and monocytes have been compared, and some effects of fixation before incubation in two incubating media of slightly differing composition for varying incubation period have been studied. The optimum staining time varies considerably and depends on the combination of fixation and incubating medium used. Commonly used methods employ long incubation periods of up to 21 h. These are not necessary and attention is drawn to a superior method which is very much quicker and gives clear staining and good cellular preservation.