Figure 5. Only polymorphic MIPs are immunogenic.

Frozen PBMCs from the MIP-negative subject were thawed and stimulated with autologous DCs pulsed with an unshared MIP detected in the other individual. Primed cells were restimulated with irradiated autologous B-LCLs pulsed with the same peptide for another 7 days. Restimulated cells were tested for in vitro cytotoxicity activity against autologous B-LCLs pulsed with the relevant peptide (positive control, black), unpulsed autologous B-LCLs (negative control, white) or MIP-positive allogeneic B-LCLs (test, grey) at various effector-to-target (E:T) ratios. The minimal cytotoxic activity against unpulsed autologous B-LCLs is most probably because of recognition of EBV epitopes. Average and s.d. of three or four independent experiments are shown. Significant differences are indicated by *P<0.05 or **P<0.01, two-tailed Student’s t-test. (a) MIPs encoded by polymorphic loci and detected exclusively in one subject. (b) MIPs encoded by non-polymorphic loci but detected exclusively in one subject.