H. Zhou et al., Heterogeneity of channel catfish CTL with respect to target recognition and cytotoxic mechanisms employed, J IMMUNOL, 167(3), 2001, pp. 1325-1332
Two types of catfish alloantigen-dependent cytotoxic T cells were cloned fr
om PBL from a fish immunized in vivo and stimulated in vitro with the allog
eneic B cell line 3B11. Because these are the first clonal cytotoxic T cell
lines derived from an ectothermic vertebrate, studies were undertaken to c
haracterize their recognition and cytotoxic mechanisms. The first type of C
TL (group 1) shows strict alloantigen specificity, i.e., they specifically
kill and proliferate only in response to 3B11 cells. The second type (group
II) shows broad allogeneic specificity, i.e., they kill and proliferate in
response to several different allogeneic cells in addition to 3B11. "Cold"
target-inhibition studies suggest that group II CTL recognize their target
s via a single receptor, because the killing of one allotarget can be inhib
ited by a different allotarget. Both types of catfish CTL form conjugates w
ith and kill targets by apoptosis. Killing by Ag-specific cytotoxic T cells
(group 1) was completely inhibited by treatment with EGTA or concanamycin
A, and this killing is sensitive to PMSF inhibition, suggesting that killin
g was mediated exclusively by the secretory perforin/granzyme mechanism. In
contrast, killing by the broadly specific T cytotoxic cells (group II) was
only partially inhibited by either EGTA or concanamycin A, suggesting that
these cells use a cytotoxic mechanism in addition to that involving perfor
in/granzyme. Consistent with the presumed use of a secretory pathway, both
groups of CTL possess putative lytic granules. These results suggest that c
atfish CTL show heterogeneity with respect to target recognition and cytoto
xic mechanisms.