InVivoMAb polyclonal rat IgG

InVivoMAb polyclonal rat IgG (Clone: Rat IgG)

Bryant-Hudson, K. M. and D. J. Carr (2012). “PD-L1-expressing dendritic cells contribute to viral resistance during acute HSV-1 infection.” Clin Dev Immunol 2012: 924619. PubMed

The inhibitory receptor, Programmed Death 1 (PD-1), and its ligands (PD-L1/PD-L2) are thought to play a role in immune surveillance during chronic viral infection. The contribution of the receptor/ligand pair during an acute infection is less understood. To determine the role of PD-L1 and PD-L2 during acute ocular herpes simplex virus type 1 (HSV-1) infection, HSV-1-infected mice administered neutralizing antibody to PD-L1 or PD-L2 were assessed for viral burden and host cellular immune responses. Virus titers were elevated in cornea and trigeminal ganglia (TG) of anti-PD-L1-treated mice which corresponded with a reduced number of CD80-expressing dendritic cells, PD-L1(+) dendritic cells, and HSV-1-specific CD8(+) T cells within the draining (mandibular) lymph node (MLN). In contrast, anti-PD-L2 treatment had no effect on viral replication or changes in the MLN population. Notably, analysis of CD11c-enriched MLN cells from anti-PD-L1-treated mice revealed impaired functional capabilities. These studies indicate PD-L1-expressing dendritic cells are important for antiviral defense during acute HSV-1 infection.

Turnquist, H. R., et al. (2011). “IL-33 expands suppressive CD11b+ Gr-1(int) and regulatory T cells, including ST2L+ Foxp3+ cells, and mediates regulatory T cell-dependent promotion of cardiac allograft survival.” J Immunol 187(9): 4598-4610. PubMed

IL-33 administration is associated with facilitation of Th2 responses and cardioprotective properties in rodent models. However, in heart transplantation, the mechanism by which IL-33, signaling through ST2L (the membrane-bound form of ST2), promotes transplant survival is unclear. We report that IL-33 administration, while facilitating Th2 responses, also increases immunoregulatory myeloid cells and CD4(+) Foxp3(+) regulatory T cells (Tregs) in mice. IL-33 expands functional myeloid-derived suppressor cells, CD11b(+) cells that exhibit intermediate (int) levels of Gr-1 and potent T cell suppressive function. Furthermore, IL-33 administration causes an St2-dependent expansion of suppressive CD4(+) Foxp3(+) Tregs, including an ST2L(+) population. IL-33 monotherapy after fully allogeneic mouse heart transplantation resulted in significant graft prolongation associated with increased Th2-type responses and decreased systemic CD8(+) IFN-gamma(+) cells. Also, despite reducing overall CD3(+) cell infiltration of the graft, IL-33 administration markedly increased intragraft Foxp3(+) cells. Whereas control graft recipients displayed increases in systemic CD11b(+) Gr-1(hi) cells, IL-33-treated recipients exhibited increased CD11b(+) Gr-1(int) cells. Enhanced ST2 expression was observed in the myocardium and endothelium of rejecting allografts, however the therapeutic effect of IL-33 required recipient St2 expression and was dependent on Tregs. These findings reveal a new immunoregulatory property of IL-33. Specifically, in addition to supporting Th2 responses, IL-33 facilitates regulatory cells, particularly functional CD4(+) Foxp3(+) Tregs that underlie IL-33-mediated cardiac allograft survival.

Carlson, M. J., et al. (2009). “In vitro-differentiated TH17 cells mediate lethal acute graft-versus-host disease with severe cutaneous and pulmonary pathologic manifestations.” Blood 113(6): 1365-1374. PubMed

The morbidity and mortality associated with graft-host-disease (GVHD) is a significant obstacle to the greater use of allogeneic stem cell transplantation. Donor T cells that predominantly differentiate into TH1/Tc1 T cells and generate pro-inflammatory cytokines such as interferon-gamma (IFN-gamma) mediate GVHD. Although numerous studies have described a pathogenic role for IFN-gamma, multiple reports have demonstrated that the lack of IFN-gamma paradoxically exacerbated GVHD lethality. This has led to speculation that another subset of T cells may significantly contribute to GVHD mortality. Several groups have demonstrated a new lineage of CD4+ T helper cell development distinct from TH1 or TH2 differentiation. This lineage is characterized by production of interleukin (IL)-17A, IL-17F, IL-22, and IL-21 and has been termed TH17 cells. Here, we demonstrate that a highly purified population of TH17 cells is capable of inducing lethal GVHD, hallmarked by extensive pathologic cutaneous and pulmonary lesions. Upon transfer, these cells migrate to and expand in GVHD target organs and secondary lymphoid tissues. Finally, we demonstrate differential roles for tumor necrosis factor-alpha (TNF-alpha) and IL-17A in the clinical manifestations of GVHD induced by TH17 cells. Our studies demonstrate that cells other than TH1/Tc1 can mediate acute GVHD.