Alloreactive CD8⁺ but not CD4⁺ T cells induce generation of bioactive IL-1β.

(A) DCs untreated (lanes 1, 2, and 5) or treated for the last 40 hours with LPS (lanes 3, 4, and 6) were challenged with alloreactive CD4⁺ (lanes 1 and 3) or CD8⁺ (lanes 2 and 4) T lymphocytes purified from the allospecific T-cell population, or with autologous CD8⁺ T lymphocytes purified from an MLR against an unrelated stimulator (Auto T cells, lanes 5 and 6) at a T-cell:DC ratio of 10:1. At the end of the coincubation cell lysates (cyt, upper panel) and supernatants (sec, bottom panel) were analyzed as for their content in IL-1β. (B) Bioactivity of secreted IL-1β: 100 μL aliquots of supernatants from the different culture conditions was added to HUVEC and incubated at 37°C for 20 hours. At the end of the incubation, the ICAM1 molecules expressed by HUVEC were quantified by ELISA.