Cd64, cd11a, and cd18 leukocytes expression in a case series of children with SARS-CoV-2 multisystem inflammatory syndrome and kawasaki disease: Similar but not the same

AIMS & OBJECTIVES: A new paediatric inflammatory syndrome named as "pediatric multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS)" has been described. It has been compared to Kawasaki Disease. The aim of this report is adding to the PIMS-TS clinical and analytical description the application of immunophenotyping by flow cytometry (FC). We describe CD64, CD18, and CD11a leukocytes expression in three children with SARSCoV2 infection and compare it with three cases of Kawasaki Disease. METHODS: Three children were studied after informed consent obtained from their parents or legal guardians. Their blood samples were collected in sterile EDTA at room temperature or refrigerated at 4°C and analyzed within 24 hours. Expressions were measured in monocytes, neutrophils, and lymphocytes. At least 10 000 events were recorded for each sample. The intensity of CD64, CD18, and CD11a surface expression were measured as mean fluorescence intensity in arbitrary units (MFI). They were compared with three previous cases of KD. RESULTS: The median CD64, CD18 and CD11a MFI expression in PIMS-TS versus KD cases are described in Figure 1. The CD64 and the CD11a expression on neutrophils and monocytes are higher. The CD11a in CD8 Lymphocytes is higher too. CONCLUSIONS: We compare for the first time the immunophenotype of children with PIMS-TS infection versus KD. We observed significant but higher upregulation of CD64, CD18, and CD11a expression. This response appears to be similar but different than in KD. Prospective studies with a higher number of cases should be conducted to confirm this observation.

Preliminary study of cd64 on monocytes and neutrophils in children with severe SARS-CoV-2 infection: Comparison with other viruses and bacteria

AIMS & OBJECTIVES: The immune response to SARSCoV-2 is not completely understood. The flow cytometry (FC) allows measuring leukocyte populations instantaneously. One of the better-studied molecules is the immunoglobulin-Fc fragment receptor I (FcγRI) or CD64. Its expression informs about the patient immune status. The aim of this study was to describe the CD64 expression in healthy children requiring pediatric intensive care unit (PICU) admission because of SARS-COV-2 infection. Later, we compare it to previous viral or bacterial infections that caused PICU admission in our centre. METHODS: Prospective observational study (March 2020 to May 2020). The percentage of CD64-positive cells and the CD64 mean fluorescence intensity (MFI) on monocytes (mCD64) and neutrophils (nCD64) were determined. The FC was done on a blood sample obtained at PICU admission. Healthy children with positive serology (IgM) or nasopharyngeal swab using real-time reverse transcriptasepolymerase chain reaction were included. The values are expressed as median and range, p < 0.05 was considered statistically significant. RESULTS: Children from the SARS-CoV-2 group were older (p= 0,000), there were no other baseline differences. CONCLUSIONS: The CD64 expression was higher compared to other causes of PICU admission. It could be linked to immune dysregulation. Prospective observational studies are needed.