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the in vivo studies by Evans (47) in another reptile, the California
desert lizard. He has shorn that antibody responses in the lizard were
inhibited if the ambient temperature was lowered from 35C to 25C,
correlating with a decrease in LPS responsiveness of alligator lympho
cytes when the ambient temperature was lowered. Evans has also shown
that even a primed lizard actively making antibody was inhibited from
making additional antibody when shifted to lower temperatures. Such a
"shutdown" of an ongoing antibody response in the lizard when moved to
lower temperatures is in marked contrast to the teleost antibody re
sponses in which antibody production continued after a shift to lower
temperatures (7). This sugests that changes in environmental tempera
ture may effect reptiles and teleosts differently. Additional experi
ments are necessary to determine if the temperature phenomena in the
alligator and the lizard are related (i.e. both are B-cell functions)
and whether monitoring in vitro LPS responses is a valid indicator of
in vivo temperature effects on the immune functions of the reptiles.
Evidence for Two Subpopulations of Lymphocytes
Several lines of evidence have been presented which argue for the
presence of at least two subpopulations in the peripheral blood of alii
gators. Briefly summarized these are 1) differences in the magnitude
of stimulation with the different mitogens, 2) differences in the com
bined effects of the mitogens, 3) a significant increase in immunoglobu
lin producing cells in LPS-stimulated cultures, 4) populations of cells
adherent or nonadherent to glass wool with different responses to LPS
and PHA, 5) the depletion of responsiveness to LPS by cytotoxic treat
ment with an anti-immunoglobulin plus complement without reducing the