Association of CD147 and Calcium Exporter PMCA4 Uncouples IL-2 Expression from Early TCR Signaling

The Ig superfamily member CD147 is upregulated following T cell activation and was shown to serve as a negative regulator of T cell proliferation. Thus, Abs targeting CD147 are being tested as new treatment strategies for cancer and autoimmune diseases. How CD147 mediates immunosuppression and whether association with other coreceptor complexes is needed have remained unknown. In the current study, we show that silencing of CD147 in human T cells increases IL-2 production without affecting the TCR proximal signaling components. We mapped the immunosuppressive moieties of CD147 to its transmembrane domain and Ig-like domain II. Using affinity purification combined with mass spectrometry, we determined the domain specificity of CD147 interaction partners and identified the calcium exporter plasma membrane calcium ATPase isoform 4 (PMCA4) as the interaction partner of the immunosuppressive moieties of CD147. CD147 does not control the proper membrane localization of PMCA4, but PMCA4 is essential for the CD147-dependent inhibition of IL-2 expression via a calcium-independent mechanism. In summary, our data show that CD147 interacts via its immunomodulatory domains with PMCA4 to bypass TCR proximal signaling and inhibit IL-2 expression

KINFix - A formalin-free non-commercial fixative optimized for histological, immunohistochemical and molecular analyses of neurosurgical tissue specimens

An optimal fixative should ideally combine the advantages of formalin fixation and freezing, allowing for good preservation of histology and molecular components, easy handling and storage, lack of toxicity, and low costs. Most of these criteria are fulfilled by ethanol-based solutions, and due to our good experience with the commercial RCL2 fixative, reflected by our published single-center trial, we initiated a multicenter ring trial. However, during its course, RCL2 was discontinued on the market. Therefore, we created our own agent, KINFix, composed of the same main constituents as RCL2, and employed it in our laboratory with similar results. Here we present our evaluation of the three fixatives formalin, RCL2, and KINFix from the perspective of histopathology as well as nucleic acid and protein analyses in comparison to fresh frozen tissues together with the multicenter ring trial data for RCL2. We observe that RCL2 and KINFix offer comparable histomorphology and superior template for molecular analyses than formalin. Moreover, KINFix as freely available fixative might overcome some of the difficulties related to the commercial agents. Therefore, we conclude that KINFix might be an attractive complement to formalin in tissue processing and advocate its use in neuropathological practice

KINFix-A formalin-free non-commercial fixative optimized for histological, immunohistochemical and molecular analyses of neurosurgical tissue specimens

An optimal fixative should ideally combine the advantages of formalin fixation and freezing, allowing for good preservation of histology and molecular components, easy handling and storage, lack of toxicity, and low costs. Most of these criteria are fulfilled by ethanol-based solutions, and due to our good experience with the commercial RCL2 fixative, reflected by our published single- center trial, we initiated a multicenter ring trial. However, during its course, RCL2 was discontinued on the market. Therefore, we created our own agent, KINFix, composed of the same main constituents as RCL2, and employed it in our laboratory with similar results. Here we present our evaluation of the three fixatives formalin, RCL2, and KINFix from the perspective of histopathology as well as nucleic acid and protein analyses in comparison to fresh frozen tissues together with the multicenter ring trial data for RCL2. We observe that RCL2 and KINFix offer comparable histomorphology and superior template for molecular analyses than formalin. Moreover, KINFix as freely available fixative might overcome some of the difficulties related to the commercial agents. Therefore, we conclude that KINFix might be an attractive complement to formalin in tissue processing and advocate its use in neuropathological practice