Impaired CD4+ and CD8+ T cell phenotype and reduced chemokine secretion in recent‐onset type 1 diabetic children
Although the role of the T cell‐mediated autoimmune reaction in type 1 diabetes (T1D) is conclusive, studies including data from human circulating CD4+ and CD8+ lymphocytes subsets during the disease onset and posterior development are scarce. Further, chemokines and chemokine receptors are key players in the migration of pathogenic T cells into the islets of non‐obese diabetic mice developing T1D, but few studies have investigated these markers in human T1D patients. We studied the expression of T helper 1 (Th1)‐ and Th2‐associated chemokine receptors, and the two isoforms of CD45 leucocyte antigen on CD4+ and CD8+ lymphocytes from T1D and healthy children, as well as the secretion of chemokines in cell supernatants in peripheral blood mononuclear cells. Our results showed increased expression of CCR7 and CD45RA and reduced CD45RO on CD8+ cells among recent‐onset T1D patients. The percentages of CD4+ cells expressing CXC chemokine receptor 3 (CXCR3), CXCR6 and CCR5, and the secretion of interferon‐γ‐induced protein‐10, monocyte chemoattractant protein‐1, macrophage inflammatory protein (MIP)‐1α and MIP‐1β was lower among diabetics. Low expression of Th1‐associated receptors and secretion of chemokines, together with an increased amount of CD8+ cells expressing CD45RA and CCR7 in T1D patients therefore might represent suboptimal Th function in T1D, leading to impaired T cytotoxic responses or alternatively reflect a selective recruitment of Th1 cells into the pancreas.