InVivoMAb anti-rat CD8α

InVivoMAb anti-rat CD8α (CLONE: OX-8)

Shibata S, Shinozaki N, Suganami A, Ikegami S, Kinoshita Y, Hasegawa R, Kentaro H, Okamoto Y, Aoki I, Tamura Y, Iwadate Y (2019). "Photo-immune therapy with liposomally formulated phospholipid-conjugated indocyanine green induces specific antitumor responses with heat shock protein-70 expression in a glioblastoma model" Oncotarget 10(2):175-183. PubMed

Glioblastoma (GBM) is the most common malignant brain tumor, and infiltrates into the surrounding normal brain tissue. Induction of a tumor-specific immune response is one of the best methods to obtain tumor-specific cytotoxicity. Photodynamic therapy (PDT) is known to effectively induce an antitumor immune response. We have developed a clinically translatable nanoparticle, liposomally formulated phospholipid-conjugated indocyanine green (LP-iDOPE), applicable for PDT. This nanoparticle accumulates in tumor tissues by the enhanced permeability and retention effect, and releases heat and singlet oxygen to injure cancer cells when activated by near infrared (NIR) light. We assessed the effectiveness of the LP-iDOPE system in brain using the rat 9L glioblastoma model. Treatment with LP-iDOPE and NIR irradiation resulted in significant tumor growth suppression and prolongation of survival. Histopathological examination showed induction of both apoptosis and necrosis and accumulation of CD8+ T-cells and macrophages/microglia accompanied by marked expressions of heat shock protein-70 (HSP70), which was not induced by mild hyperthermia alone at 45° C or an interleukin-2-mediated immune reaction. Notably, the efficacy was lost in immunocompromised nude rats. These results collectively show that the novel nanoparticle LP-iDOPE in combination with NIR irradiation can efficiently induce a tumor-specific immune reaction for malignant gliomas possibly by inducing HSP70 expression which is known to activate antigen-presenting cells through toll-like receptor signaling.

Hartlage AS, Murthy S, Kumar A, Trivedi S, Dravid P, Sharma H, Walker CM, Kapoor A (2019). "Vaccination to prevent T cell subversion can protect against persistent hepacivirus infection" Nat Commun 10(1):1113. PubMed

Efforts to develop an effective vaccine against the hepatitis C virus (HCV; human hepacivirus) have been stymied by a lack of small animal models. Here, we describe an experimental rat model of chronic HCV-related hepacivirus infection and its response to T cell immunization. Immune-competent rats challenged with a rodent hepacivirus (RHV) develop chronic viremia characterized by expansion of non-functional CD8⁺ T cells. Single-dose vaccination with a recombinant adenovirus vector expressing hepacivirus non-structural proteins induces effective immunity in majority of rats. Resolution of infection coincides with a vigorous recall of intrahepatic cellular responses. Host selection of viral CD8 escape variants can subvert vaccine-conferred immunity. Transient depletion of CD8⁺ cells from vaccinated rats prolongs infection, while CD4⁺ cell depletion results in chronic viremia. These results provide direct evidence that co-operation between CD4⁺ and CD8⁺ T cells is important for hepacivirus immunity, and that subversion of responses can be prevented by prophylactic vaccination.

Nuccitelli R, Berridge JC, Mallon Z, Kreis M, Athos B, Nuccitelli P (2015). "Nanoelectroablation of Murine Tumors Triggers a CD8-Dependent Inhibition of Secondary Tumor Growth" PLoS One 10(7):e0134364. PubMed

We have used both a rat orthotopic hepatocellular carcinoma model and a mouse allograft tumor model to study liver tumor ablation with nanosecond pulsed electric fields (nsPEF). We confirm that nsPEF treatment triggers apoptosis in rat liver tumor cells as indicated by the appearance of cleaved caspase 3 and 9 within two hours after treatment. Furthermore we provide evidence that nsPEF treatment leads to the translocation of calreticulin (CRT) to the cell surface which is considered a damage-associated molecular pattern indicative of immunogenic cell death. We provide direct evidence that nanoelectroablation triggers a CD8-dependent inhibition of secondary tumor growth by comparing the growth rate of secondary orthotopic liver tumors in nsPEF-treated rats with that in nsPEF-treated rats depleted of CD8+ cytotoxic T-cells. The growth of these secondary tumors was severely inhibited as compared to tumor growth in CD8-depleated rats, with their average size only 3% of the primary tumor size after the same one-week growth period. In contrast, when we depleted CD8+ T-cells the second tumor grew more robustly, reaching 54% of the size of the first tumor. In addition, we demonstrate with immunohistochemistry that CD8+ T-cells are highly enriched in the secondary tumors exhibiting slow growth. We also showed that vaccinating mice with nsPEF-treated isogenic tumor cells stimulates an immune response that inhibits the growth of secondary tumors in a CD8+-dependent manner. We conclude that nanoelectroablation triggers the production of CD8+ cytotoxic T-cells resulting in the inhibition of secondary tumor growth.

Wallgren AC, Karlsson-Parra A, Korsgren O (1995). "The main infiltrating cell in xenograft rejection is a CD4+ macrophage and not a T lymphocyte" Transplantation 60(6):594-601. PubMed

Porcine fetal islet-like cell clusters (ICC) or isolated rat islets were implanted under the kidney capsule of normoglycemic rats. The animals were sacrificed 1, 3, 6, 12, or 24 days after transplantation, and a detailed morphological and phenotypic characterization of the different cellular subtypes infiltrating the xenograft was performed and compared with the rejection of allogeneic islets. In xenograft rejection a progressive infiltration of large, polygonal, macrophage-like cells, which with time became the dominating cellular subtype, occurred. These cells expressed the CD4 antigen and the macrophage-specific ED1 antigen. From day 6 and onward, a majority of the macrophage-like cells also expressed the CD8 antigen and the macrophage-specific differentiation antigen ED2. T lymphocytes, defined by their TCR alpha/beta or CD2 expression, were found in low numbers and mainly in the periphery of the graft. At the later stages of xenorejection a substantial number of eosinophilic granulocytes were also found. The allograft rejection, on the contrary, was characterized by a progressive infiltration of T lymphocytes, which with time became the dominating cellular subtype. No clear immunoglobulin or complement deposition was seen in the transplants before day 12, when IgG deposition was found in central necrotic areas of the xenograft. Previous experiments in rodents have underlined the crucial importance of CD4 positive cells in the xenograft rejection process. However, in none of these studies it was conclusively demonstrated that the CD4-expressing cells were T lymphocytes. The presence of CD4-expressing macrophages heavily infiltrating the porcine xenograft seen in our study may thus be in agreement with previous studies in which the anti-CD4 reactive cells were erroneously designated T lymphocytes. Interestingly, the findings in xenograft rejection in the present study have striking similarities with the defense mechanisms active against infections by large parasites such as helminths.