IFNγ and IL-4 production by CD4, CD8 and WC1 γδ TCR⁺ T cells from cattle lymph nodes and blood

The synthesis of IFNγ and IL-4 by CD4, CD8 and WC1 γδ TCR+ T cell sub-populations, and T cells stained with activation/memory-sub-set markers has been examined by flow cytometric analysis. Cells from blood, prescapular, bronchial and mesenteric lymph nodes and Peyer's patches were incubated with phorbol 12-myristate 13-acetate (PMA), ionomycin and brefeldin-A before staining. Lymphocytes that stained for cytoplasmic IFNγ were evident within the CD4 and CD8 populations from all tissues and also in the WC1 population from lymph nodes. IL-4 producing cells were primarily evident within the CD4 population. IFNγ synthesis was evident within both CD45RO+ and CD45RB+ populations, but IL-4 synthesis was predominantly by cells that were CD45RO+/CD45RB-. Expression of CD62L is not related to functional memory in CD4+ T cells from cattle and CD62L+ cells, particularly from the lymph nodes draining the skin and the lungs, stained with mAb to IFNγ and IL-4. The findings indicate that at least for CD4+ T cells, where CD45 isoform expression is related to functional memory, these two cytokines are produced predominantly by cells with a memory phenotype. The observation that some WC1+ cells produce IFNγ implies the presence of distinct sub-sets of this γδ TCR+ population cattle and suggests a functional role. Copyright © 2001 Elsevier Science B.V.