CD7 identifies 2 distinct populations of CD56⁺ cells. (A) CD3/14/19^neg cells were gated for CD56 expression and CD56⁺ cells were plotted against CD7 to determine the percentage of CD7⁺ cells within the CD56 gate. In peripheral blood, as many as 10% of CD56⁺ CD3/14/19^neg cells are CD7^neg. (B) Classically defined NK cells (CD3^negCD56⁺CD16^+/neg) were gated and plotted against CD7 versus CD16 to identify 4 populations of cells. Each population was then overlaid back to a CD56 versus CD16 plot to observe where the CD7^neg non–NK-cell subsets were distributed among the CD7⁺ NK cells. (C) Similarly, CD56^dim/negCD16⁺ cells were gated and plotted against CD7 versus CD16. Although approximately 43% of the CD56^dim/negCD16⁺ population was CD7⁺ NK cells, there was extensive overlap with the CD7^neg cell fraction. (D) CD4⁺CD56⁺ cells were assessed for CD7 expression. On average, less than 50% of CD4⁺CD56⁺ cells coexpress CD7 (n = 6).