Figure 1. Concentration dependent suppression of T cell proliferation by CyaA and ET.

(A) [³H]-thymidine uptake by PBL stimulated for 48 h by CD3 cross-linking in the presence or absence of the indicated concentrations of CyaA (top) or ET (bottom). The results, obtained on triplicate samples of PBL from 5 independent donors, are expressed as % [³H]-thymidine uptake (cpm) by CyaA or ET treated cells compared to control cells stimulated in the absence of either toxin (taken as 100%). The arrow shows the toxin concentration selected for the polarization experiments (CyaA, 0.28 nM; ET, 0.11 nM). (B) [³H]-thymidine uptake by PBL stimulated for 48 h by CD3 cross-linking in the presence or absence of either CyaA and ET or the respective adenylase deficient mutants (45 nM CyaA/CyaA-E5, 110 nM ET/EL1). The results are expressed as in A. ***P≤0.001; **P≤0.01; *P≤0.05. Error bars, SD.