Effects of Recombinant SARS-CoV-2 Spike Protein Variants on Platelet Morphology and Activation.

Platelets are central elements of hemostasis and also play a pivotal role in the pathogenesis of thrombosis in coronavirus disease 2019. This study was planned to investigate the effects of different severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recombinant spike protein variants on platelet morphology and activation. Citrated whole blood collected from ostensibly healthy subjects was challenged with saline (control sample) and with 2 and 20 ng/mL final concentration of SARS-CoV-2 recombinant spike protein of Ancestral, Alpha, Delta, and Omicron variants. Platelet count was found to be decreased with all SARS-CoV-2 recombinant spike protein variants and concentrations tested, achieving the lowest values with 20 ng/mL Delta recombinant spike protein. The mean platelet volume increased in all samples irrespective of SARS-CoV-2 recombinant spike protein variants and concentrations tested, but especially using Delta and Alpha recombinant spike proteins. The values of both platelet function analyzer-200 collagen-adenosine diphosphate and collagen-epinephrine increased in all samples irrespective of SARS-CoV-2 recombinant spike protein variants and concentrations tested, and thus reflecting platelet exhaustion, and displaying again higher increases with Delta and Alpha recombinant spike proteins. Most samples where SARS-CoV-2 recombinant spike proteins were added were flagged as containing platelet clumps. Morphological analysis revealed the presence of a considerable number of activated platelets, platelet clumps, platelet-monocyte, and platelet-neutrophils aggregates, especially in samples spiked with Alpha and Delta recombinant spike proteins at 20 ng/mL. These results provide support to the evidence that SARS-CoV-2 is capable of activating platelets through its spike protein, though such effect varies depending on different spike protein variants.

Effect of syringe underfilling on the quality of venous blood gas analysis.

OBJECTIVES: There is limited information on the influence of collecting small amounts of blood on the quality of blood gas analysis. Therefore, the purpose of this study was to investigate the effects of different degrees of underfilling of syringes on test results of venous blood gas analysis. METHODS: Venous blood was collected by venipuncture from 19 healthcare workers in three 1.0 mL syringes for blood gas analysis, by manually aspirating different volumes of blood (i.e., 1.0, 0.5 and 0.25 mL). Routine blood gas analysis was then immediately performed with GEM Premier 5,000. The results of the two underfilled syringes were compared with those of the reference syringe filled with appropriate blood volume. RESULTS: The values of most assayed parameters did not differ significantly in the two underfilled syringes. Statistically significant variations were found for lactate, hematocrit and total hemoglobin, the values of which gradually increased as the fill volume diminished, as well as for sodium concentration, which decreased in both insufficiently filled blood gas syringes. The bias was clinically meaningful for lactate in syringe filled with 0.25 mL of blood, and for hematocrit, total hemoglobin and sodium in both syringes containing 0.5 and 0.25 mL of blood. CONCLUSIONS: Collection of smaller volumes of venous blood than the specified filling volume in blood gas syringes may have an effect on the quality of some test results, namely lactate, hematocrit, total hemoglobin and sodium. Specific indications must be given for standardizing the volume of blood to be collected within these syringes.

Incomplete filling of spray-dried K2EDTA evacuated blood tubes: impact on measuring routine hematological parameters on Sysmex XN-10.

OBJECTIVES: Because there is little published evidence on the effects of incomplete filling of K2EDTA evacuated blood tubes on routine hematological testing, this original study aimed to provide updated information on this preanalytical aspect. METHODS: The study population consisted of 17 ostensibly healthy volunteers. Blood was drawn by venipuncture with a 10 mL syringe and dispensed in varying amounts (0.2, 0.5, 1.0, 2.0, and 3.0 mL) into 3.0 mL blood tubes containing spray-dried 5.4 mg K2EDTA. All tubes were gently mixed and used to perform routine hematology tests on the Sysmex XN-10. Clinically significant variations were defined when the limits of desirable specifications of bias derived from biologic variation were exceeded. RESULTS: The desirable bias was exceeded in 33 % filled tubes (1.0 mL) for hematocrit and MCV (increased values) and for MCHC (decreased values), while it was exceeded in 17 % filled tubes (0.5 mL) for hemoglobin, hematocrit and MCV (increased values), and for MCHC (decreased values). Finally, the variation of values was higher than the desirable bias for RBC, hemoglobin, hematocrit and MCV (increase), and for MCHC and MPV (decrease) in 7 % filled tubes (0.2 mL). No clinically significant variations were observed in tubes filled up to 67 % of their nominal volume (i.e., 2.0 mL). CONCLUSIONS: Consideration should be given to reject spray-dried K2EDTA blood tubes that contain a blood volume <67 % of the nominal fill volume, as biased laboratory data in these samples may interfere with clinical decision making and care management.

Effects of Different Types of Recombinant SARS-CoV-2 Spike Protein on Circulating Monocytes' Structure.

This study investigated the biological effects on circulating monocytes after challenge with SARS-CoV-2 recombinant spike protein. Whole blood collected from seven ostensibly healthy healthcare workers was incubated for 15 min with 2 and 20 ng/mL final concentration of recombinant spike protein of Ancestral, Alpha, Delta, and Omicron variants. Samples were analyzed with Sysmex XN and DI-60 analyzers. Cellular complexity (i.e., the presence of granules, vacuoles and other cytoplasmic inclusions) increased in all samples challenged with the recombinant spike protein of the Ancestral, Alpha, and Delta variants, but not in those containing Omicron. The cellular content of nucleic acids was constantly decreased in most samples, achieving statistical significance in those containing 20 ng/mL of Alpha and Delta recombinant spike proteins. The heterogeneity of monocyte volumes significantly increased in all samples, achieving statistical significance in those containing 20 ng/mL of recombinant spike protein of the Ancestral, Alpha and Delta variants. The monocyte morphological abnormalities after spike protein challenge included dysmorphia, granulation, intense vacuolization, platelet phagocytosis, development of aberrant nuclei, and cytoplasmic extrusions. The SARS-CoV-2 spike protein triggers important monocyte morphological abnormalities, more evident in cells challenged with recombinant spike protein of the more clinically severe Alpha and Delta variants.