Phagocytic leukocytes were separated from the peripheral blood of chic
kens using a one-step Percoll density gradient technique. Heterophils
recovered from two fractions of the gradient were of 96.9 to 99.8% pur
ity and were fully viable and functional, as demonstrated by their cap
acity to phagocytose latex beads and staphylococci. Adherent mononucle
ar cells were cultured from specific gradient fractions and shown to p
hagocytose staphylococci.