Of distinct costimulatory molecules by APCs influences T cell activation, cytokine production and transition to memory. To address this premise we beganJ Immunol. Author manuscript; offered in PMC 2011 September 15.CXCR2 Proteins Biological Activity NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptEllis et al.Pageby performing cell surface staining on each the APCs and T cells just before and soon after in vitro stimulation with antigen. Accordingly, purified DC subsets, macrophages and B cells had been stained for surface expression of B7.1, B7.2, CD40, PD-L1, and PD-L2 each ahead of and right after incubation with Ag and DO11.10 T cells (Fig. five). The information presented in Figure 5A shows that before culture with T cells, CD8+ DCs and B cells have greater expression of PD-L2 (73.six and 72.1 , respectively) than CD8-CD4-, CD8-CD4+ or macrophages. It truly is interesting to note that the CD8-CD4- DCs, which are capable of inducing long-lived T cells that usually do not mount a memory response have an intermediate degree of PD-L2 (41.three) in comparison with CD8-CD4+ DCs (28.three) and macrophages (26.1). B7.1 and B7.two molecules are hugely expressed on CD8+ DCs but not on B cells and hence might not correlate with memory development. Right after incubation with Ag and DO11.ten T cells, the expression of B7.1, B7.2, CD40, PD-L1 and PD-L2 on CD8+ DCs remained at Leukocyte Elastase Inhibitor Proteins MedChemExpress levels comparable to those observed before Ag stimulation (Fig. 5B). For B cells, CD40, PD-L1 and PD-L2 expression also remained at levels comparable to these observed prior to Ag stimulation but B7.1 and B7.two had a slight raise in their expression. Interestingly, even though the expression of CD40, B7.1, B7.two and PD-L1 on CD8-CD4-, CD8-CD4+, and macrophages remained comparable to levels observed before Ag stimulation, the expression of PD-L2 enhanced on all kinds of APCs. All round, PD-L2 expression was high on CD8+ DCs and B cells prior to and after Ag stimulation but elevated around the other APCs immediately after stimulation with Ag, possibly suggesting that PD-L2 effects transition to memory when expressed on the APCs at the beginning of interaction with T cells. If PD-L2 on APCs plays a part within the induction of T cell memory, its receptor PD-1 should be accessible around the T cells to facilitate interactions with APCs and transition of T cells from effector to memory precursors. To begin investigation in the function PD-L2/PD-1 interactions could play inside the transition of T cell memory we tested the T cells for expression of PD-1 at the same time as other markers which include CCR7, CD28, and IL-7R ahead of and just after stimulation with Ag. Figure six shows that before Ag stimulation, the T cells express PD-1 substantially but CCR7, CD28 and IL-7R were at basal levels (Fig. six, prime panel). When PD-1 is normally at low levels on na e polyclonal T cells (44), the larger PD-1 expression observed right here might be connected towards the fact that the DO11.10 T cells are homogeneous TCR transgenic T cells that come from a lymphopenic atmosphere. Subsequent to stimulation with Ag presented on specific APCs, the expression of PD-1 increased from 78.1 to 95.7 when the APCs have been CD8+DCs, remained at similar levels as prior to stimulation when the APCs have been CD8- DCs or B cells and decreased to 53 with macrophages (Fig six. panels 2-6). The expression of CCR7, CD28 and IL-7R improved considerably except when the presenting cells have been B cells where CCR7 and IL-7R remained at basal levels. These final results indicated the na e T cells within this model express PD-1, the ligand for PD-L2 and sustain it at a important level dur.