label: Abnormal CD69 upregulation upon TCR activation
label_lc: abnormal cd69 upregulation upon tcr activation
description: "Any abnormality in the upregulation of CD69 on T cells after activation via the T cell receptor (TCR). Upregulation of CD69 is one of the earliest and most sensitive measures of antigen recognition in the periphery, and transient expression of CD69 is associated with positive selection in the thymus."