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\nIntroduction: Serologic characterization of antihuman platelet antigen (HPA) alloantibodies is crucial in fetal neonatal alloimmune thrombocytopenia. The gold standard MAIPA assay requires fresh platelets from HPA-genotyped donors, which is challenging for some laboratories. Megakaryocytes express HPA epitopes and offer an alternative source for detecting anti-HPA antibodies. The objective of this study was to assess the efficacy of a novel assay called monoclonal antibody immobilization of megakaryocyte antigens (MAIMA) for detecting anti-HPA antibodies. Methods: CD34+ cells from buffy coats were differentiated into megakaryocytes in vitro. The performance of the MAIMA assay was evaluated using WHO reference reagents for HPA-1a, HPA-3a, and HPA-5b, along with sera samples from patients who had well-characterized anti-HPA antibodies. Results: The WHO anti-HPA-1a reference reagent showed similar binding to megakaryocytes and platelets in MAIMA and MAIPA, respectively. On the other hand, optical density (OD) values for the WHO anti-HPA-3a reference reagent were lower in MAIMA than in MAIPA. Anti-HPA-5b antibodies were not detectable in MAIMA. Patients’ sera containing anti-HPA-1a antibodies were successfully detected in MAIMA in all clinical samples. Moreover, OD values in MAIPA and MAIMA showed high correlation (r = 0.96, p < 0.001). MAIMA was reactive for samples with anti-HPA-3a as well as anti-HPA-3b; however, OD values were lower compared to MAIPA. Interestingly, all patient samples with anti-HPA-5b antibodies were tested negative in MAIMA. Conclusion: In vitro generated megakaryocytes can be used to detect anti-HPA-1a alloantibodies. However, despite this potential, they may be less suitable for the detection of alloantibodies against other HPAs such as HPA-5b. The identification of antibodies to human platelet antigens (HPA) is crucial. The standard test (MAIPA assay) is difficult because it requires fresh platelets from specific donors. This study investigated a new method, monoclonal antibody immobilization of megakaryocyte antigens (MAIMA), using in vitro generated megakaryocytes from CD34+ cells. The assay was tested against WHO reference reagents and patient samples with known anti-HPA antibodies. Results showed that MAIMA successfully detected anti-HPA-1a antibodies and correlated well with MAIPA. However, MAIMA had lower sensitivity for anti-HPA-3a and anti-HPA-5b antibodies. Notably, anti-HPA-5b antibodies were not detectable by MAIMA. In conclusion, in vitro generated megakaryocytes can effectively detect anti-HPA-1a antibodies. However, MAIMA may be less suitable for antibodies against other HPAs, such as HPA-5b. This study highlights the potential of MAIMA as an alternative assay and provides insight into its strengths and limitations in detecting specific anti-HPA antibodies. [ABSTRACT FROM AUTHOR]

Background: The prevalence of COVID-19 breakthrough infections in healthcare workers (HCWs) remains an issue of concern. This study examines the different characteristics associated with breakthrough infections in HCWs. Methods: From the total participants in the TüSeRe:exact study (n = 1046), we specifically included study participants who had received three vaccinations and were not infected prior to the third vaccination. Participants were invited to complete an online questionnaire, which included inquiries about any breakthrough infections they might have experienced. Univariate Cox regression analysis was used to investigate the association between participant characteristics and breakthrough infections. Results: Among 629 HCWs (497 female and 132 male), 241 (38%) experienced breakthrough infections during the follow-up period. The frequency of breakthrough infections was 39.2% (195/497) among female participants and 34.8% (46/132) among male participants (p = 0.357). The Cox regression model adjusted for age and sex showed that participants with cardiovascular disease (hazard ratio (95%CI) = 0.621 (0.392–0.985); p = 0.043) and those taking antihypertensives (hazard ratio (95%CI) = 0.551 (0.331–0.915); p = 0.021) had a significantly lower hazard ratio for breakthrough infections. The use of analgesics after the first vaccine (hazard ratio (95%CI) = 1.343 (1.025–1.759); p = 0.032) was associated with an increased risk of breakthrough infections. Conclusions: These findings can inform targeted preventive measures and risk management strategies to protect frontline workers and maintain a resilient healthcare system during the ongoing pandemic. [ABSTRACT FROM AUTHOR]

Background: Transfusion of platelets is a life-saving medical strategy used worldwide to treat patients with thrombocytopenia as well as platelet function disorders. Summary: Until the end of 1960s, platelets were stored in the cold because of their superior hemostatic functionality. Cold storage of platelets was then abandoned due to better posttransfusion recovery and survival of room temperature (RT)-stored platelets, demonstrated by radioactive labeling studies. Based on these findings, RT became the standard condition to store platelets for clinical applications. Evidence shows that RT storage increases the risk of septic transfusion reactions associated with bacterial contamination. Therefore, the storage time is currently limited to 4–7 days, according to the national guidelines, causing a constant challenge to cover the clinical request. Despite the enormous efforts made to optimize storage conditions of platelets, the quality and efficacy of platelets still decrease during the short storage time at RT. In this context, during the last years, cold storage has seen a renaissance due to the better hemostatic functionality, reduced risk of bacterial contamination, and potentially longer storage time. Key Messages: In this review, we will focus on the impact of cold storage on the in vitro platelet functions as promising alternative storage temperature for future medical applications. [ABSTRACT FROM AUTHOR]

As the Corona Disease 2019 (COVID-19) caused by SARS-CoV-2 persists, vaccination is one of the key measures to contain the spread. Side effects (SE) from vaccination are one of the reasons for reluctance to vaccinate. We systematically investigated self-reported SE after the first, second, and booster vaccinations. The data were collected during the TüSeRe: exact study (Tübinger Monitoring Studie zur exakten Analyse der Immunantwort nach Vakzinierung). Employees of health and research institutions were invited to participate. Study participants were asked to fill out an online questionnaire and report their SE after each dose of SARS-CoV-2 vaccination. A total of 1046 participants (mean age: 44 ± 12.9 years; female, n = 815 (78%); male, n = 231 (22%)) were included in the analysis. Local and systemic SE were more frequent after receiving the vector-based vaccine ChAdOx1 nCoV-19 in the first vaccination. However, local and systemic SE were more common after receiving mRNA vaccines (BNT162b2, mRNA-1273) in the second vaccination. Compared to the BNT162b2 vaccine, more SE have been observed after receiving the mRNA-1273 vaccine in the booster vaccination. In multivariate analysis, local and systemic side effects were associated with vaccine type, age and gender. Local and systemic SE are common after SARS-CoV-2 vaccines. The frequency of self-reported local and systemic SE differ significantly between mRNA and vector-based vaccines. [ABSTRACT FROM AUTHOR]