KLRK1 and obstructive sleep apnea syndrome: PCR analysis of PBMCs (Fig 5A) from these same tumor-bearing, but non-study patients showed a statistically greater expression of circulating CD3 transcripts compared to CD8 and NKG2D, and the expression of these transcripts in PBMCs was approximately 100-fold greater than the respective expression in OSA tumor tissue (P < 0.0001).