Objective. CC chemokines and their receptors play a fundamental role in trafficking and activation of leukocytes at sites of inflammation, contributing to joint damage in rheumatoid arthritis. Met-RANTES, an amino-terminal-modified methionylated form of RAN-TES (CCL5), antagonizes the binding of the chemokines RANTES and macrophage inflammatory protein 1␣ (MIP-1␣; CCL3) to their receptors CCR1 and CCR5, respectively. The aim of this study was to investigate whether Met-RANTES could ameliorate adjuvantinduced arthritis (AIA) in the rat.Methods. Using immunohistochemistry, enzymelinked immunosorbent assay, real-time reverse transcription-polymerase chain reaction, Western blot analysis, adoptive transfer, and chemotaxis, we defined joint inflammation, bony destruction, neutrophil and macrophage migration, Met-RANTES binding affinity to rat receptors, proinflammatory cytokine and bone marker levels, CCR1 and CCR5 expression and activation, and macrophage homing into joints with AIA.Results. Administration of Met-RANTES as a preventative reduced the severity of joint inflammation. Administration of Met-RANTES to ankles with AIA showed decreases in inflammation, radiographic soft tissue swelling, and bone erosion. Met-RANTES significantly reduced the number of neutrophils and macrophages at the peak of arthritis compared with salineinjected controls. Competitive chemotaxis in peripheral blood mononuclear cells demonstrated that Met-RANTES inhibited MIP-1␣ and MIP-1␤ at 50% inhibition concentrations of 5 nM and 2 nM, respectively. Furthermore, levels of tumor necrosis factor ␣, interleukin-1␤, macrophage colony-stimulating factor, and RANKL were decreased in joints with AIA in the Met-RANTES group compared with the control group. Interestingly, the expression and activation of CCR1 and CCR5 in the joint were down-regulated in the Met-RANTES group compared with the control group. Functionally, Met-RANTES administration decreased adoptively transferred peritoneal macrophage homing into the joint.Conclusion. The data suggest that the targeting of Th1-associated chemokine receptors reduce joint inflammation, bone destruction, and cell recruitment into joints with AIA.

Purpose: To investigate the antitumor efficacy of T-cell anergy reversal through homeostatic proliferation and regulatoryT-cell (Treg) depletion in a clinically relevant murine adoptive immunotherapy model. Experimental Design: B16 melanoma cells were engineered to express the model SIYRYYGL (SIY) antigen to enable immune monitoring. Tumor-specificTcells expanded in tumor-challenged wild-type hosts but became hyporesponsive. To examine whether lymphopenia-induced homeostatic proliferation could reverse tumor-induced T-cell anergy, total splenicTcells were transferred into lymphopenic RAG2 -/-mice or control P14/RAG2 -/-mice. Tumor growth was measured, and SIY-specific immune responses were monitored using ELISPOT and SIY/K b tetramers. To determine whether Treg depletion could synergize with homeostatic proliferation, RAG2-/-mice received total or CD25-depleted T cells, followed or preceded by B16.SIY challenge. This approach was further investigated in wild-type mice lymphodepleted with sublethal total body irradiation. Results: Adoptive transfer of total splenic T cells into RAG2-/-mice moderately affected the growth rate of B16.SIY. As Treg expansion occurred in tumor-bearing mice, CD25 + T cells were depleted from totalTcells before adoptive transfer. Interestingly, transfer of CD25-depletedT cells into RAG2-/-mice resulted in potent rejection of B16 melanoma in both prophylactic and shortterm preimplanted tumor settings and was associated with maintained T-cell effector function. Using a clinically applicable approach, wild-type mice were lymphodepleted using sublethal total body irradiation, which similarly supported tumor rejection upon transfer of CD25-depleted Tcells. Conclusions: Our results indicate that combined CD25 depletion and homeostatic proliferation support a potent antitumor immune responseöan approach with potential for clinical translation.

PD-1 is a receptor inducibly expressed on CD4+ and CD8+ T cells following activation. PD-1-deficient mice develop signs of autoimmunity, suggesting a negative regulatory role for PD-1 in dampening lymphocyte responses. The expression of one ligand for PD-1, designated PD-L1 or B7-H1, on tumor cells of a variety of histologies has suggested a potential mechanism for tumor escape from immune destruction. This review summarizes data regarding PD-1 and related negative regulatory receptors, focusing on implications for potentiating antitumor immunity in vivo.