engleski

Differences in NK cell subsets and expression of activating and inhibiting receptors in infants

Infants are more prone to infections than adults since their immune system is still not completely developed. Natural killer (NK) cells play an important role in the first line of defense against viral infection. They can be immunophenotyped regarding specific CD56 and CD16 (FcγRII) expression. and according to this divided into two subsets ; major CD56+CD16+ and minor CD56- CD16+ NK cells with diminished cytotoxic activity. Although, NK cell cytotoxicity is dependent on the interaction between different NK receptors (NKR) and target cell ligands, the balance between engagement of activating and inhibiting NKR determines outcome. PBMC were isolated from healthy adults, healthy infants and RSV infected hospitalized infants. NK cell subsets were distinguished based on antibody staining and were additionally stained with noncommercial antibodies for NK receptors (LIR1, KIR2DL2, NKp46, NKp80, NKG2D or CMRF). Different proportion of NK cell subsets were noticed in infants compared to adults. CD56+CD16+ cells were predominant in all tested groups, while CD56-CD16+ cells, although scarce in adults, represented one third of total NK cells in infants. Those two subsets of NK cells also revealed some differences regarding NKR expression in both infants and adults. In adults CD56+CD16+ cells had higher percentages of activating receptors (NKp46, NKp80, NKG2D and CMRF) compared to CD56-CD16+ cells. In healthy and RSV infected infants, inhibiting receptors (LIR1 and KIR2DL2) tended to be lower on CD56+CD16+ cells compared to healthy adults. Comparison of NKR between two examined NK cell subsets showed lower expression of NK activating receptors on CD56-CD16+ NK cells. The fact that CD56-CD16+ cells represent significant proportion of total NK cells in infants might be the reason for lower overall NK activity. Lower CMRF and NKG2D expression on NK cells in healthy and RSV-infected infants impose lower activating potential and contribute to the weaker antiviral response in infants.

NK cells; NK receptors; infants; RSV

nije evidentirano