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Peculiar Imunophenotype of Peripheral Blood Lymphocytes in Three Cases with Persistent Isolated Lymphocytosis after Covid-19 Vaccination
International Journal of Laboratory Hematology ; 45(Supplement 1):195-196, 2023.
Article in English | EMBASE | ID: covidwho-2219077
ABSTRACT

Introduction:

Transient increase in the lymphocyte count (lymphocytosis) is a common laboratory finding caused by acute (usually viral) infections. When persistent lymphocytosis prolonged for several months is found in otherwise healthy individuals, flow cytometry immunophenotyping (FCI) of peripheral blood lymphocytes is required to rule out lymphoproliferative disorder. Here, we presented the immunophenotype analysis of lymphocytes in three cases with persistent isolated lymphocytosis after vaccination for coronavirus disease 2019 (COVID-19). Novel vaccines contain glycolipids that activate natural killer T-cells (NKT-cells), a subset of T-cells that have properties of both T-cells and NK-cells. NKT-cells normally constitute 1-2 % of all peripheral blood T-cells. Activation of NKT-cells by vaccines enchance both the innate and adaptive immune response to the vaccine. Method(s) Three patients were admitted to the Department of Clinical Hematology of the University Hospital Osijek to determine the cause of isolated lymphocytosis in differential blood count with normal leukocyte count, accidentaly detected by regular check-ups. For that purpose, FCI analysis of peripheral blood lymphocytes was requested. Approximately 4 months ago, two patients were vaccinated with mRNAbased COVID-19 vaccine and the third one with adenovirus-based vaccine. Persistence of ymphocytosis was monitored 3-4 months after it was first observed. Result(s) FCI analysis of lymphocytes in all three blood samples showed T-cell proliferation (>80 % of all lymphocytes). A high percentage of cells within the gate of all T-cells (medians 13 %, 29 % and 48 %) expressed surface markers CD2+CD3+CD5+(moderate to dim expression)CD7+CD8+CD16+56+, corresponding to immunophenotype of NKT-cells. Conclusion(s) The results showed that NKT-cells were the dominant subset of T-cells underlying lymphocytosis, regardless of the type of COVID-19 vaccine used. Also, isolated lymphocytosis after COVID-19 vaccination can persist for more than 3 months. COVID-19 vaccines contain glycolipids to facilitate vaccine entry into cells, but as shown here, they probably activate NKT-cells as well. The problem with FCI analysis of such cases is that the immunophenotype of NKT-cells does not differ from the immunophenotype of T-cell large granular lymphocytic leukemia (T-LGL) cells. Future post-vaccination lymphocytosis studies should explain mechanisms of NKT-cell activation with COVID-19 vaccines and determine exactly when to raise the alarm for a more detailed analysis of such cases.
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Collection: Databases of international organizations Database: EMBASE Topics: Long Covid / Vaccines Language: English Journal: International Journal of Laboratory Hematology Year: 2023 Document Type: Article

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Collection: Databases of international organizations Database: EMBASE Topics: Long Covid / Vaccines Language: English Journal: International Journal of Laboratory Hematology Year: 2023 Document Type: Article