Background: Class-I MHC-restricted T cell-associated molecule (CRTAM) is a protein expressed by activated natural killer T (NKT) cells, natural killer (NK) cells, CD8 T cells, and certain CD4 T lymphocytes. It is also expressed in Purkinje neurons and epithelial cells. However, no studies have examined the expression of CRTAM in peripheral blood cells during homeostasis or disease. Therefore, we explored whether CRTAM expression is influenced by the presence of allergic asthma.
Methods: We collected whole peripheral blood cells from non-asthmatic control subjects (n = 17) and patients with asthma (n = 17). All patients with asthma tested positive in allergen skin prick tests. We analyzed CRTAM expression in CD4(+) and CD8(+) T lymphocyte populations. CRTAM expression was also analyzed in CD177(+) neutrophils and IL5Rα(+) eosinophils.
Findings: The percentage of CD4(+)CRTAM(+) and CD8(+)CRTAM(+)T lymphocytes in peripheral blood was higher in allergic asthma patients compared with healthy controls. Furthermore, the percentage of CD177(+)CRTAM(+) neutrophils in peripheral blood was also elevated in patients with allergic asthma. However, the percentage of IL5Rα(+)CRTAM(+) eosinophils in peripheral blood was not significantly different in patients with allergic asthma compared with healthy controls.
Conclusions: CRTAM expression on T cells, eosinophils, and neutrophils may be involved in bronchial inflammation in allergic asthma. Determination of CRTAM expression in peripheral blood may be useful for the diagnosis of bronchial inflammation and/or to identify recently activated immune cells.
Keywords: Asthma; CD355; CD4 T cell; CD8 T cells; CRTAM; Eosinophils; Neutrophils.