49
organs. All cell suspensions used contained < 30% red blood cells and
'v 7-10% phagocytic cells (determined by colloidal carbon untake).
Control (no SRBC) or immunized (with SRBC) cultures were assayed
for PFC in the Jerne hemolytic plaque assay after incubation at 22C
and 32C for various time periods. Two experiments utilizing unimmunized
"normal" bluegill as cell donors are presented in Table 11. In 32C
incubated cultures there were significant increases in the number of
PFC of immunized cultures over control culture responses. The maximum
PFC response as well as the maximum number of recovered cells frojn
immunized than control cultures occured on day 7. More cells were
recovered from immunized than control cultures and on day 7 more than
the initial (Day 0) number of cells were present in immunized cultures.
Viability in the cultures did not change over the ten-day culture
period.
In contrast to the 32C incubated cultures, cultures maintained at
22C did not show a PFC response. There was no significant difference
between control and immunized cultures and the viability was lower after
ten days. *
One preliminary experiment was done with cells from an immunized
bluegill in order to determine if a secondary immunization in vitro
would increase the number of responsive cells. Unlike cells from normal
fish, the PFC response in this fish was observed to occur only at 22C.
The magnitude of the response measured on day 7 however was much lower
(control =  PFC, "boosted" = 18 PFC/Culture) than that seen at 32C
v/ith cells from normal animals. It should be pointed out that the
number of recovered cells in the single experiment conducted was higher
in 22C incubated cultures (22C, 90% for controls, 285% for boosted;