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To summarize the comparisons with mammalian B-cells, the data
suggest the alligator has a B-like lymphocyte population which is
1) present in low numbers in the peripheral blood, 2) responsive to
BPS, 3) adherent to glass wool and 4) has immunoglobulin present on its
cell surface.
In mammalian tissue culture studies a positive mixed lymphocyte
reaction is an accepted measure of cell mediated immunity, i.e. a T-cell
function. Again arguing by analogy, the data from mixed lymphocyte
cultures of alligator peripheral blood lymphocytes would indicate,that
the alligator also has a T-like cell involved in cell mediated reactions.
However, since it has not been proven that the B-like cells rather than
T-like cells are the responding cells in the alligator mixed lymphocyte
reaction, such conclusions should be approached with caution.
Recent experiments have demonstrated that both T- and B-cells are
involved in mixed lymphocyte reactions in the human (57). The B-cell
population was shown to be the stimulating population (elicits the re
sponse) whereas the T-cells were the effector cells (undergo stimulation).
The magnitude of the T-cell stimulation was dependent on the number of
B-cells present. With this in mind the mixed lymphocyte culture experi
ments need to be redone, monitoring the LPS responsiveness as well as
the PHA responsiveness, to determine if the spectrum of low to high re
sponses can be correlated with the magnitude of the LPS responses of
the B-like cells.
Further evidence for the presence of a T-like lymphocyte in the
peripheral blood of the alligator was supported by its mammalian T-cell
characteristics (54) of insensitivity to anti-immunoglobulin plus comple
ment cytotoxicity, nonadherence to glass wool or nylon wool (with the