PHENOTYPIC AND FUNCTIONAL CHARACTERIZATION OF PERIPHERAL T CELL POPULATIONS FROM COVID-19 PATIENTS HOSPITALIZED IN HOSPITAL PRIVADO UNIVERSITARIO CÓRDOBA- ARGENTINA

ONOFRIO, L *; DUTTO, J *; BOSSIO, S *; BAIGORRI, RE *; BRUGO, MB *; ALMADA, L **; MARIN, C **; RUIZ MORENO, F **; VOLPINI, X **; ALMEIDA, M; OLIVERA, C; PONCE, NE; QUIROZ, JN; SILVERA RUIZ, S; BOFELLI, L; ACOSTA RODRIGUEZ, EV; AMEZCUA VESELY, C; ARROYO, D; CERBAN, F; CERVI, L; FOZZATTI, L; ICELY, P; IRIBARREN, P; MALETTO, B; MORON, G; RODRIGUEZ GALAN, MC; STEMPIN, C; ABIEGA, C; ESCUDERO, D; KAHN, A; CAEIRO, JP; MACCIONI, M; MOTRAN, C; CHIAPELLO, L; MONTES, C; GRUPPI, A; SOTOMAYOR, C; GRUPO IMMUNOCOVIDCBA.

Reunión de Sociedades de Biociencias 2021 - LXIX REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA.

Congreso; Reunión de Sociedades de Biociencias 2021 - LXIX REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA; 2021

Sociedad Argentina de Inmunologia

*All these authors contributed equally. **All these authors contributed equally. SARS-CoV-2 infection results in asymptomatic, mild or severe disease. T cells could contribute to these different outcomes, but it remains unclear whether T cell response is dysfunctional or excessive.Here, we evaluated the phenotypic and functional features of circulating T cells from a cohort of 40 COVID-19 patients (Cpts) with moderate (MOD) and severe (SEV) clinical disease (aged 21-80 years) and 14 aged matched healthy controls (HC) by FACS. All Cpts exhibited a reduced frequency of CD3+T and Tregs cells compare to HC (p< 0.05). When exhaustion was evaluated, SEV Cptsshowed higher % of PD-1+ and CD39+ in T conv cells (p<0.05), whereas no differences were found in BTLA or TIGIT expression. Even though, no differences in cytokine production (INF-γ, IL-2 andTNF) were observed, T conv cells from SEV Cpts showed a higher % of GZMB+ and CD107+ cells than MOD Cpts or HC (p<0.05). Circulating CD8+ T cells express different levels of CD8, where CD8lo cells represent highly activated cytotoxic T cells. COVID-19 patients presented a higher % of CD8lo T cells than controls and this increment was even more pronounced in SEV Cpts (p=0.04, MD vs HD; p=0.0012, SD vs HD). CD8lo T cells exhibited impaired cytokine production and CD107a expression compared to CD8hi T cells, although GZMB levels were similar among both CD8+ subsets. CD8lo population from HC showed higher % of naïve T cells than effector memory (EM)(p=0.04) or EMRA (p=0.008) subsets, but this distribution was not seen in MOD or SEV Cpts. Indeed, MOD or SEV Cpts showed higher % of EM cells than HC. Conclusion: the disease severity impacts on the phenotype and functional features of CD4+ and CD8+ T cells, with a pronounced increment in the % of CD8lo T cells as the disease worsens. These cells appear to have dysfunctional phenotype with an impairment of effector cytokines production but maintaining cytotoxic potential.The CD8hi/CD8lo ratio might be a useful parameter to predict the disease outcome.