FIG 4.

Proliferation of, and IFN-γ release by, bovine lymph node cells isolated postmortem and restimulated ex vivo for 5 days with either 5 μg/ml ConA, medium only, 5 μg/ml EHEC O157:H7 T3SPs from the sepL deletion strain Zap1143 (ΔsepL) or its isogenic wild-type (WT) strain Zap193, or medium containing a matched concentration of commercial EHEC O111:B4 LPS. ΔsepL T3SP preparations contain mainly secreted effector proteins, while WT T3SP preparations consist mainly of structural translocon components. The use of these two different T3SP preparations allows the relative contributions of structural and effector proteins to antigen recall responses to be compared. Cells were isolated from rectal lymph nodes (RLN), mesenteric lymph nodes (MLN), and prescapular lymph nodes (PsLN). (A and B) Proliferation (A) and IFN-γ release (B) are expressed as indices, representing fold changes in the response to T3SPs from levels with the relevant LPS controls. Circles represent individual animals. (C and D) Interaction plots illustrate mean thymidine incorporation (C) and IFN-γ release (D) by lymph node cells from each experimental group in response to different stimuli. Error bars represent predicted means and 95% confidence intervals from linear-mixed-model analysis.