Estimation of KLRK1 (NKG2D) and 4-1 BB Gene expression as a biomarker for prognosis and diagnosis of Severe COVID-19

The complications of the respiratory system, that demining from pneumonia to acute respiratory distress syndrome, are the marker to disease severity of COVID-19. Natural killer (NK) is innate immune cells that contribute in body defense against viral infections; a decrease in these cells affects the development and severity of  COVID-19. The study consists of 34 cases diagnosed as severe COVID-19, 19 females and 15 males aged  (23-75) years, who attended Al- Diwaniyah teaching hospital during the period (October 2023- July 2024). The healthy group included 20 samples, 13 males and 7 females aged (27-61) years. After diagnosis of COVID-19 -2 by the positive result of RT-PCR  from nasopharyngeal specimens and chest CT scan,  RNA was extracted from the blood specimens for measuring mRNA KLRK1 and 4-1BB via RT- qPCR technique.  The result in the research revealed lower KLRK1 mRNA in patients with COVID-19 (0.51 ±0.25) compared to the healthy group  (1.22 ±0.56), while 4-1BB was elevated in patients with COVID-19  (2.07±0.94) compared to the healthy group (1.21±0.58)  at a significant level (P ≤ 0.01). This study indicated that the deceased mRNA KLER1 and elevated 4-1BB in COVID-19 patients might be an independent biomarker for prognosis and diagnosis of the severity of COVID-19 infection.