A FLOW CYTOMETRIC EVALUATION OF B LYMPHOCYTE CELLS AND SUBGROUPS OF CHILDREN DIAGNOSED WITH COVID-19

Abstract

Objective: During viral infections, antibody production of B cells are critical for protective immunity. It is known that the COVID-19 disease has a milder course in children. It is crucial to evaluate the causes of this situation from a pediatrician's perspective to determine the treatment goals of the disease. We aimed to examine the flow cytometric changes in B cells and subtypes observed in children diagnosed with the COVID-19 infection. Materials and Methods: This is a prospective cohort study including 22 children aged 0-18 who had been diagnosed with COVID-19. CD19(+)B cells, CD27(-)IgD(+) naive B, CD21(low )immature B, CD21(low)CD38(low) active B, CD27(-)IgD(-) double-negative B, CD27(-) non-memory B, CD27(+) memory B, CD27(+)IgD(-) switched memory B, and CD27(+)IgD(+) non-switched memory B cells were studied using flow cytometry. Results: B cells counts decreased as a percentage in the 2-5 years age group and the 10-16 age group as an absolute number. Naive and non-memory B cell frequencies increased in the 5-10 years old and over 16 years old groups. Double negative B cells were normal in all age groups. Non-memory B cells increased in the 5-10 and over 16 years old groups, whereas memory B cells decreased. In all groups, switched memory B cells decreased. Non-switched memory B cell counts were within reference ranges in all groups except for the over 16 years group. Conclusion: Although the decrease in B cell count is associated with the severity of the disease, naive B cell subgroups did not decrease in the pediatric patients included in the study. All groups showed increased switched memory B cell counts, in accordance with the literature. Unlike adults, naive B cells, non-switched memory B cells, and double-negative B cells were normal in children.