Mehmet Fatih ORHAN, Öner ÖZDEMİR, Gülay TRAK

COVID-19 Tanılı Çocuklarda T Hücreleri ve Alt Grupları

Amaç: COVID-19 hastalığında, T lenfositlerin sayısal olarak azaldığı, hem CD4+ hem de CD8+’in azalabildiği, bazen de CD8+ düzeyinin anlamlı arttığı görülmüştür. Virüse spesifik CD8+ T-hücrelerin Efektör bellek (TEM) veya RA+ Terminal diferansiye efektör bellek (TEMRA) hücrelerinin olduğu düşünülmektedir. Ancak bu hücrelerin özellikleri, özellikle SARS-CoV-2 enfeksiyonu veya COVID-19 hastalığının patogenezindeki rolleri belirsizdir. Bu araştırmada, SARS-CoV-2 PCR pozitifliği ile COVID -19 hastalığı tanısı alan çocuk hastalarda tanı sırasında yardımcı T, sitotoksik T hücreleri ve alt tiplerinde gözlenen değişiklikleri akım hücre ölçer ile irdelemeyi amaçladık. Yöntem: COVID-19 tanısı alan, 0-18 yaş arası 22 çocuğa flow sitometri ile; T Yardımcı Hücresi (TH), T Sitotoksik Hücresi (TC), T Naif Hücreleri (TN), Santral bellek (TCM), Efektör bellek (TEM), RA+ Terminal diferansiye efektör bellek (TEMRA) ve Son timik göçmen T hücreleri (RTEs) çalışılmıştır. Bulgular: T hücre sayıları tüm yaş gruplarında normal bulundu. CD4/CD8 oranı 5 yaş altı ve 16 yaş üstü grupta arttı. CD4+T hücreler içinde TCM 16 yaş üstü grupta azalırken, TEM tüm yaş gruplarında azaldı. RTEs, 16 yaş üstü grup hariç diğerlerinde azaldı. Naif CD8+T hücreleri (TN) tüm yaş gruplarında yüksek bulundu. Sonuç: Düşük sayıda saptanan CD4+ ve CD8+ lenfosit sayısı, 2019 Coronavirus hastalığında (COVID-19) ayırt edici bir laboratuvar bulgusu olarak bildirilmiştir. Yeterli sayıda naif T hücresine sahip olmak, bağışıklık sisteminin bilinmeyen patojenlere sürekli yanıt vermesi için gereklidir. Çocuklarda bu hücrelerin normalden yüksek olduğu bu çalışma tespit edilmiştir.

Anahtar Kelimeler:

Çocuk, İmmünoloji, COVID-19, T-lenfosit alt grupları, Akım hücre ölçer

T Cells and Subgroups in Children with COVID-19

Objective: In COVID-19 disease, it was observed that T lymphocytes decreased numerically, both CD4+ and CD8+ could decrease, and sometimes the CD8+ level increased significantly. The virus-specific CD8+ T-cells are thought to be TEM or TEMRA cells. However, the characteristics of these cells, particularly their role in the pathogenesis of SARS-CoV-2 infection or COVID-19 disease, are unclear. Therefore, this study aimed to examine the flow cytometric changes observed in T helper, T cytotoxic cells, and subtypes during diagnosis in pediatric patients diagnosed with COVID-19 infection with SARS-CoV-2 PCR positivity. Methods: Twenty-two children aged 0-18, diagnosed with COVID-19, with flow cytometry; T Helper Cell (TH), T Cytotoxic Cell (TC), T Naive Cells (TN), Central Memory (TCM), Effector Memory (TEM), RA + Effector memory (TEMRA) and Recent Thymic Emigrants (RTEs) were studied. Results: T cell counts were found to be expected in all age groups. The CD4/CD8 ratio increased in the under-five and over 16 age group. While TCM among CD4+T cells decreased in the group above 16 years of age, TEM decreased in all age groups. RTEs decreased in all except the age group 16+. Naive CD8+ T cells (TN) were found to be high in all age groups. Conclusion: A low number of CD4+ and CD8+ lymphocytes have been reported as a distinctive laboratory finding in 2019 Coronavirus disease (COVID-19). Having enough naive T cells is essential for the immune system to respond consistently to unknown pathogens. This study found that these cells were higher than expected in children.

Keywords:

Child, Immunology, COVID-19, Flow Cytometry, T-Lymphocyte Subsets,

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