Peripheral blood natural killer cells activation status determined by CD69 upregulation predicts implantation outcome in IVF

Abstract

Problem: NK lymphocytes play critical yet poorly defined role in implantation and during development in early pregnancy.

Methods of study: Recently, we showed that the proportion of NK that expressed CD69⁺ after incubation with K562 (CD69(stim)) cells reflected the NK population excitation potential. In the present study, we investigate the significance of NK activation levels in predicting embryo implantation.

Results: A qualitative analysis of values distribution in two groups showed that 25/33 (75.8%) women who became pregnant had CD69(stim) levels that were >30 but <60% (conditionally normal zone). In contrast, CD69(stim) levels in patients who failed to become pregnant were either elevated, as in 10/51 (19.6%), or reduced, as in 20/51 (39.2%) of the patients. Accentuated CD69(stim) levels were predictive for implantation failure, extremely significant for decreased (OR 6.9, p=0.0004) and not quite significant for increased CD69(stim) levels (OR 3.9, p=0.062). Accordingly, conditionally normal CD69(stim) levels were favourable for implantation (OR 4.46, p=0.0032).

Conclusion: We confirm that actual peripheral blood natural killer cells activation status have an influence on embryo implantation. We showed that exactly normal NK cell activity predicting successful implantation.

Keywords: CD69 expression; Embryo implantation; NK activity; NK stimulation; Natural killer lymphocytes.