CD244 and activated PI3K-delta syndrome: Most importantly, we observed a significant increase in the frequency of CD8+ T cells expressing all three inhibitory receptors, PD-1, CD244, and CD160 (PD-1+CD160+CD244+), in the APDS patients which was 20 ± 5.6% compared with 6 ± 2.3% PD-1+ CD160+CD244+CD8+ T cells in healthy controls.