Analysis of functional heterogeneity of porcine memory CD4+ T cells

Previous studies have identified swine helper memory T cells as CD4+CD8α+SLADR+. We have recently described a new porcine surface antigen (2E3) selectively expressed on CD4+ T cells that allows to divide these cells into naïve (2E3+) and effector/memory (2E3−). However, although the majority of CD4+2E3− cells are CD8α+SLADR+, a minor proportion do not express SLADR and/or CD8α. Here, we have analyzed the functional capacity of these CD4+2E3− subsets to proliferate to a recall antigen. Both SLADR− and CD8α− cells proliferated in response to lysozyme, but at lower levels compared to the whole population CD4+2E3−. Besides, after activation with PMA plus ionomycin, CD4+2E3−SLADR− T cells produced IFNγ and TNFα, although they did also in lower proportion than the whole CD4+2E3− population. Most of the IFNγ−TNFα+, IFNγ+TNFα+, IFNγ+TNFα− cells were CD8α+ and CD45RA−, while IFNγ−TNFα− cells showed a less differentiate phenotype.