CD28 and Crohn disease: According to our study, the percentage of HLA-DR+ CD4+ T cells in lymphocytes was positively associated with the development of Crohn disease, whereas IgD− CD27− B cells in lymphocytes, CD28 on CD39+ secreting CD4 Treg cells, and percentage of naïve CD4+ T cells were negatively related to the development of Crohn disease.