Which CD markers are alpha/beta double-negative T cells (DNTs) lacking?

Alpha/beta double-negative T cells (DNTs) are a distinct subset of T cells characterized by their lack of both CD4 and CD8 markers. These markers are typically associated with conventional T cells, where CD4+ T cells are often helper T cells and CD8+ T cells are cytotoxic T cells. The absence of CD4 and CD8 helps to define the DNTs, indicating that they do not fit the standard profiles of helper or cytotoxic T cells.

DNTs can still express other T cell-associated markers, which helps them perform specific immune functions despite not having these core surface markers. Hence, the identification of DNTs relies strongly on their expression of surface proteins, where the loss of CD4 and CD8 is the defining feature of this T cell population.

The other options involve markers that do not directly define the double-negative phenotype in T cells, as they are specific cell surface proteins associated with different cell types or other aspects of T cell functionality. For example, CD3 is a T cell receptor complex component, CD19 is a B cell marker, and CD25 and CD56 are associated with different immune cell functionalities, further demonstrating that the most relevant defining markers in this context are indeed CD4