103
LPS response had disappeared. Upon returning alligator X to an outdoor
environment for three months (May, June and July) the LPS responsive
cells were again detectable (S.I.'s for LPS and PHA were 5 and 72 re
spectively) .
Evidence for Two Populations of Alligator Lymphocytes
Differences in the magnitude of the stimulation obtained with the
different mitogens as well as variations in the combined effects of dif
ferent mitogens suggested that there may be at least two types of lym-
phocytes responding in mitogenic assays. The following results are
from experiments designed to demonstrate that at least two different
lymphocyte populations are present in cell suspensions isolated by
Hypaque-Ficoll from the peripheral blood of alligators. To limit the
number of variables tested, PHA and LPS were the primary mitogens used
to follow mitogen responses after various cell manipulations.
Experiments were designed to determine if different populations of
lymphocytes could be separated on the basis of their adherence or non
adherence to nylon wool or glass wool. Cells passed through columns
*
filled with nylon wool or glass wool could be separated into two frac
tions; nonadherent and adherent fractions. These fractions were then
cultured with various mitogens to determine if they exhibited differ
ences in responses to mitogen stimulation. Nylon wool columns proved
ineffective in that there was no difference between the nonadherent and
adherent fractions in response to PHA, LPS, Con A, or PWM stimulation.
However cell fractions obtained fi*om glass wool columns did show differ
ent mitogen responses. In three experiments the nonadherent cells re-
producibly exhibited significantly (p < 0.05) higher PHA (and Con A)