The Equine CD4+ Lymphocyte Proteome

CD4+ T cells are key players in immunology and disease pathology, including relapsing autoimmune uveitis. Equine recurrent uveitis is the only spontaneous animal model for this disease in man. Knowledge about the CD4+ cell proteome is crucial for studies on possible changes in proteome expression of CD4+ effector cells in disease. For this purpose, we generated a reference dataset of the equine CD4+ cell proteome by sorting equine CD4+ lymphocytes followed by analysis of whole cell lysate as well as membrane protein fraction using mass spectrometry. 1. Introduction CD4+ lymphocytes play a major role in several immunological processes and diseases, including autoimmune uveitis [1]. Several experimental animal models exist for this disease; however, due to striking immunopathological and clinical similarities, equine recurrent uveitis is the only spontaneous model for relapsing autoimmune uveitis in man [2]. Equine recurrent uveitis is an autoimmune mediated disease affecting horses worldwide [3]. It presents with painful, remitting-relapsing inflammatory attacks of inner eye structures alternating with stages of quiescence [4]. Directly prior to a uveitic attack, immune cells are activated in periphery, migrate into the eye, and attack the retina [5–7]. These cells infiltrating the eye are mainly CD4+ T cells with a Th1 phenotype [7, 8]. Knowledge on the protein repertoire of CD4+ cells is crucial for the investigation of potential changes in protein expression occurring in these cells in course of immune reactions. To create a solid fundament for further studies, we generated a table of all proteins expressed in CD4+ cells (Dataset Item 1 (Table)) as well as a separate table comprising only membrane associated proteins (Dataset Item 2 (Table)). For this purpose, CD4+ lymphocytes were isolated from total equine lymphocytes by fluorescence activated cell sorting. Subsequently, we extracted membrane proteins from these cells and analyzed this protein fraction using mass spectrometry. In parallel, we performed mass spectrometry analysis on whole CD4+ cell lysates (Figure 1). Figure 1: Complete workflow for our study. Left panel shows isolation and staining of equine lymphocytes, middle panel shows cell sorting, and right panel shows further processing of sorted cells for mass spectrometry analysis. The two dataset items presented in this study give a detailed description of the physiological CD4+ immune cell proteome repertoire and set a reference for further comparative proteomic studies on activated cells or those altered in course of disease. 2.