Morphology and Immunophenotype Correlation Study of Peripheral Blood from COVID19 Patients

ABSTRACT

Background: Since the first case of COVID19 infection in 2019, this RNA virus has led an unprecedented pandemic that infected more than 232 million people. Although the disease is studied extensively, much remains poorly understood. Here, we performed the first correlation study on the peripheral blood morphology and immunophenotype of the white blood cells (WBCs) from COVID19 patients. Design: A total of 52 samples from COVID19 patients and 15 blood samples as control group were analyzed. COVID19 patients were divided into two groups based on clinical severity, severe (respiratory failure) or non-severe (hospitalized but stable). The controls were the patients with negative COVID19 results by PCR and antibody tests. The WBC morphology was examined either by blood smear review or via CellaVision DM analyzer captured images. Navios flow cytometer and Beckman Kaluza C software were used for immunophenotype analysis. Two-tailed T-test was performed on the COVID19 groups and the control group Results: Almost all COVID19 patients showed marked neutrophilia and lymphopenia on the CBC tests. Morphologically, the neutrophils showed irregularities like hypogranulation, toxic granules and pseudo Pelger-Huet anomaly (Fig 1A). In severe COIVD19 group, there was an increase in neutrophils with immatures phenotypes, showing CD33 positivity while CD10, CD13 and CD16 negative (Fig 1B). Conversely, the CD10(+) mature neutrophils aberrantly expressed CD56 (Fig 1B). The percentage of CD56(+) neutrophils was significantly higher in both COVID19 groups, suggesting a stronger cellular adhesion and interaction. The monocytes from the COVID19 patients had increased cytoplasm with cytoplasmic protrusion and vacuolization (Fig 2A). Phenotypically they were positive for CD13, CD33, CD38 and HLA-DR. The lymphocytes were also atypical, including increased cytoplasm with large granules and vacuoles. Phenotypically, they are activated, expressing CD38, HLA-DR, and mainly α/β subtype. Giant platelets with cytoplasmic vacuoles and projections were easily seen. Platelet aggregations were observed (Fig 2B). These platelets were CD45(-) and expressed CD61 at lower-than-normal intensity, while expressing increased CD42b intensity when compared to the control group on a log scale. Conclusions: Despite being a small study, we were able to correlate the morphologic and phenotypic alterations of the WBCs in COVID19 patients. As such, this helped to explain some of the clinical hematologic manifestation of the disease. (Figure Presented).