In rodents, dietary supplementation with spray-dried porcine plasma (SDP) attenuates lymphocyte activation in Peyer’s patches and mesenteric lymph nodes and improves the intestinal epithelial barrier function during intestinal inflammation induced by S. aureus enterotoxin B (SEB). The objective of this study was to discern the molecular mechanisms involved in the intestinal protective effects of SDP. To perform the experiments, male C57BL/6 mice (n=24) were used. Experimental diets were administered for 14 d starting at weaning (day 19). Mice were challenged with a single SEB dose (25 µg/mice, i.p) at day 32 and killed 24 h later. Mice were randomly distributed in three groups: CTL group, fed a control diet (in which SDP was substituted by milk proteins); SEB group, fed a control diet and administered with SEB; and SDP group, fed a diet supplemented with 8% SDP and challenged with SEB. MLN lymphocytes were stained and analysed by flow cytometry. The expression of cytokines (IL-10 and TGFβ1), adhesion molecules (Madcam-1 and ICAM-1) and transcription factors (Smad2/3 and NFκB) in the intestinal mucosa were determined by real-time PCR and by Western blot. Results (means ± SEM; n=8) were analysed by one way ANOVA. SEB administration increased the MLN cell recruitment (SEB: 34.9×109 ± 3.0×109 vs CTL: 22.9×109 ± 1.7×109, p<0.05), the percentage of activated Th lymphocytes (SEB: 8.3 ± 0.5 vs CTL: 3.6 ± 0.1, p<0.05) and the activated to regulatory Th lymphocytes ratio (SEB: 3.0 ± 0.2 vs CTL: 1.3 ± 0.1, p<0.05). SDP diet prevented all these effects (p<0.05). The enterotoxin administration did not change the mucosal expression of IL-10 and TGFβ1, but SDP supplementation increased the expression of both cytokines when compared to the SEB group (SDP: 5.5 ± 1.0 vs SEB: 1.2 ± 0.2; SDP: 2.6 ± 0.4 vs SEB: 1.0 ± 0.1, p<0.05 respectively). The administration of enterotoxin increased 6-fold the expression of Madcam-1 and ICAM-1 (p<0.001) and these effects were attenuated by SDP supplementation (p<0.05). SEB also decreased Smad2/3 phosphorylation and augmented NFκB phosphorylation (SEB: 0.8 ± 0.0 vs CTL: 1 ± 0.1; SEB: 1.5 ± 0.1 vs CTL: 1.0 ± 0.1, p<0.05, respectively) without affecting their total expression. SDP prevented the effects of SEB on both transcription factors (p<0.05). Our results indicate that SDP modulates the immune response in challenged animals through regulation of transcription factors and adhesion molecules that, in turn, will reduce intestinal cell infiltration and the magnitude of the inflammatory response.