Differential cytokine mRNA expression in single lymphatic follicles of the calf ileal and jejunal Peyer's patches

The ruminant gut-associated lymphoid tissues are broadly classified into ileal and jejunal Peyer's patches (PP). We isolated single lymphatic follicles from ileal and jejunal PP and examined mRNA expression of 13 cytokines using RT-PCR. Four patterns of differential expression were identified. In Pattern 1, the cytokines IL-7, IL-10, IL-12, and IL-18 were detected in all follicles of both ileal and jejunal PP. In Pattern 2, the cytokines IL-2, IL-4, and IL-13 were expressed in most jejunal PP follicles, but were undetectable in the ileal PP follicles. The cytokines characterizing Pattern 3 (IL-1β, IFN-γ, and IL-6) were detected in all follicles of the jejunal PP, but were differentially expressed in each follicle of ileal PP. In Pattern 4, the cytokines IL-8, TNF-α, and GM-CSF were variably expressed in follicles of both ileal and jejunal PP. More detailed knowledge about differential expression of cytokines in ileal and jejunal PP will facilitate a better understanding of the immune responses of primary and secondary lymphoid organs in the bovine small intestine.