Studies with isolated cells are important to the understanding of mech
anisms by which eosinophils participate in allergic inflammation, Due
to species variability, isolation techniques and cell biology need to
be defined for each source, We developed methods to obtain rat eosinop
hils with purity and viability exceeding 90%, characterized the supero
xide anion production of these cells in response to standard activator
s, and compared these results with those previously obtained in our la
boratories with the use of human eosinophils, Rat eosinophils responde
d vigorously to phorbol myristate acetate and poorly to platelet-activ
ating factor and to N-formyl-methionyl-leucyl-phenylalanine, parallel
to the responses of human eosinophils, In contrast, rat eosinophils re
sponded unlike human eosinophils to other activators, having a larger
response to calcium ionophore A23187, a smaller response to serum-trea
ted or serum-opsonized zymosan, and a negative rather than positive mo
dulatory effect of cytochalasin B. We conclude that rat eosinophils ca
n be obtained in high purity and with intact responsiveness to a numbe
r of different activators.