Syrian Hamster Anti-Mouse KLRG-1 Monoclonal antibody, clone 2F1 Functional Grade

This work sought to confirm the human-like expression of exhaustion and senescence markers in a mouse model with a humanized immune system (HIS): the Balb/c Rag2(KO) IL2rgc(KO) Sirp alpha(NOD) Flk2(KO) HLA-A2(HHD) (BRGSF-A2) mouse reconstituted with human CD34(+) cord blood cells. With regard to senescence markers, the percentage of CD57(+) T cells was higher in the bone marrow (BM) than in the spleen or blood. The same was true for KLRG1(+) hCD8(+) T cells. With regard to exhaustion markers, the percentage of programmed death 1 (PD-1(+)) T cells was higher in the BM than in the spleen or blood; the same was true for TIGIT(+) hCD4(+) cells. These tissue-specific differences were related to both higher proportions of memory T cells in BM and intrinsic differences in expression within the memory fraction. In blood samples from HIS mice and healthy human donors (HDs), we found that the percentage of KLRG1(+) cells among hCD8(+) T cells was lower in HIS compared to HDs. The opposite was true for CD4(+) T cells. Unexpectedly, a high frequency of KLRG1(+) cells was observed among naive T cells in HIS mice. CD57 expression on T cells was similar in blood samples from HIS mice and HDs. Likewise, PD-1 expression was similar in the two systems, although a relatively low proportion of HIS hCD4(+) T cells expressed TIGIT. The BRGSF-A2 HIS mouse's exhaustion and senescence profile was tissue specific and relatively human like; hence, this mouse might be a valuable tool for determining the preclinical efficacy of immunotherapies.

Natural killer (NK) cells are innate effector cells with critical roles not only in tumor immunosurveillance and viral immunity, but also in bacterial and fungal infections. Toll-like receptor 2 (TLR2) can be important in the early and sustained immune responses to pathogens and tumors through the induction of cytokines and chemokines that recruit and activate immune effector cells. We investigated the role of TLR2 activation in NK cell recruitment with a view to informing approaches to induce or regulate peritoneal NK cell responses therapeutically. Peritoneal injection of TLR2 activators, including peptidoglycan and the lipopeptides FSL-1 and Pam(3)CSK(4), resulted in NK cell recruitment after 16 h with increased NK cell numbers maintained for 48 h. TLR2 activators induced large amounts of CCR2 ligands, but much smaller amounts of CCR5 and CXCR3 ligands. Consistent with this observation, NK cell migration was abrogated in CCR2-deficient mice after peritoneal FSL-1 injection. Adoptive transfer of CCR2-deficient NK cells prior to peritoneal FSL-1 activation confirmed a cell-intrinsic component of CCR2-mediated NK cell migration. TLR2 activation did not induce an activated NK cell phenotype, but significant changes included an increase in the KLRG1(+)subset and decreased NKG2D expression. Although not activatedin vivo, peritoneal NK cells could be activated by interleukin (IL)-12 and IL-18ex vivoto express CD69 and interferon gamma. These data demonstrate that TLR2-mediated immune activation is a potent inducer of NK cell recruitment via a CCR2-dependent mechanism and that NK cells recruited by this mechanism can respond to additional signals to exert effector cell functions.