#5548 THE PROGNOSTIC VALUE OF LYMPHOCYTE SUBSETS IN ANTIBODY RESPONSE AFTER SARS-COV2 VACCINATION IN DIALYSIS PATIENTS AND KIDNEY TRANSPLANT RECIPIENTS

Abstract Background and Aims Mortality due to SARS-COV-2 infection in hemodialysis (HD) patients kidney transplant recipients (KTRs) is high. Despite intensive vaccination programs these vulnerable populations, the adequacy of respective generated immune responses significantly lower than general population additional booster doses have been recommended by multiple health systems World Health Organization. The humoral cellular remain still under further study HD KTRs. aim our was determine predictive value lymphocyte subpopulations production antibodies against SARS-CoV-2 after second dose vaccine. Method cohort this prospective (ClinicalTrials.gov, NCT04932876) included 34 54 KTRs who received two BNT162b2 (Pfizer–BioNTech). Lymphocyte subpopulations, including B cells, CD4+ CD8+ T cells as well naïve memory lymphocytes among others were analyzed flow cytometry at three time points, before (T0), 2nd (T1), 2 weeks (T2). Exclusion criteria previous SARS-CoV2 during follow-up. anti-SARS-CoV2 antibody (Ab) response assessed using ARCHITECT IgG II Quant test (Abbott). Titers >50 arbitrary units (AU)/ml considered positive for seroconversion T1 T2. A linear regression model applied separately subgroups patients. Results mean age transplanted 58.5 years while 68.5 age. analysis revealed that populations CD19+ lymphocytes, CD3+CD16+56+ CD4+CD45RO can predict formation (p-ANOVA<0.001) based on model: Ab = 4869+519*CD19-226*CD3+CD16+56-139* CD4+CD45RO. CD45RA+CD45RO CD4 CD8 ratio, CD3-CD16+56+ 20267+835.3*CD19-286*CD45RA+CD45RO-375.2*CD4+ CD45RO+851*CD4/CD8-187.3*CD3-CD16+56+. models explain variation dependent variable (Ab), according adjusted ${{\rm{R}}^2}$ index, a rate 24% 67% respectively. possible residual autocorrelation (DW statistic >DU>DL both models). No multicollinearity observed (All VIF< 1). Normality residuals homoscedasticity also met models. Conclusion Quantification appears significant prognostic regarding development SARS-CoV-2, especially Of particular interest are differences related between KTRs, more sub-populations appear influence generation compared above patients' specific subpopulations. More studies needed validate