Evaluation of NK cell quantity and function in a patient suspected of having an NK cell deficiency syndrome

IEIs: inborn errors of immunity; NK: natural killer; EBV: Epstein-Barr virus; CMV: cytomegalovirus; VZV: varicella-zoster virus; HSV: herpes simplex virus.

* Refer to the UpToDate topic on the clinical manifestations and diagnosis of NK cell deficiency syndromes, section on differential diagnosis.

¶ While the chromium release assay is the "gold standard," it is increasingly difficult to access clinically and flow cytometric surrogate assays are also acceptable.

Δ Variants known to cause classical and functional NK cell deficiencies, respectively, are discussed in the text of the UpToDate topic on clinical manifestations and diagnosis of NK cell deficiency syndromes.