Characterization of NK cells present in pediatric patients? tonsils in the context of EBV infection: An immature population?

FERRESSINI GERPE, NM; MOYANO A; CALDIROLA MS; DE MATTEO E; PRECIADO MV; GAILLARD, M. I.; PAOLA ANDREA CHABAY

Congreso; Reunión Anual Sociedades de Biociencia. SAIC. SAI. SAFIS. 2020; 2020

SAIC

In children, NK cells play a fundamental role in the asymptomatic infection by EBV. It was described that the NKG2A+ subpopulation can successfully controls both primary infection and EBV-mediated transformation in children from developed countries.In this study we characterized the NK cells in the tonsils of a cohort of 47 pediatric patients infected or not with EBV. We defined EBV status by serological assay, the presence of CD56, IFNγ and Granzyme B (GzB) by immunohistochemistry (IHC), and the expression of CD56. CD16. NKG2D, NKG2A, CD57, CD34 and IFNγ production by flow cytometry (FC).We characterized 9 primary infected patients (PI); 27 healthy carriers (HC), patients going through viral reactivation (R) and 4 non-infected patients (NI). The IHC assay did not show differences between groups in the mean counts of CD56, IFN or GzB (p> 0,05 in all cases; Kruskal-Wallis test). By FC, we did not observe a particular increase in the IFNγ production in either (p>0,05; Kruskal-Wallis test). The two major subpopulations of NK cells in the tonsils were CD56Bright (40,5%) and CD56DimCD16- (42,2%), without difference among EBV-infection groups (p>0,05; Kruskal- Wallis test). CD56Bright NKG2D-NKG2A- subpopulation prevailed in the four groups, particularly in older HC patients (r=0.6173, p=0.0325, Spearman correlation test). CD56DimCD16- cells displayed less proportion of NKG2D-NKG2A+ y NKG2D+NKG2A+ subpopulations (p= 0,0369 and p= 0,0011 respectively, Kruskal-Wallis test). Preliminary assays targeting the expression of markers of maturity showed high levels of CD43+ cells (28,04% + 17,40) and low proportion of CD57+ cells (13,38% + 9,43). This study reveals the presence of a NK subpopulation with signs of less developed cells, which could be related with a deficient control of the EBV infection. Further assays are required in order to determine the functionality of this potentially immature population.