Immunological imprint of COVID-19 on human peripheral blood leukocyte populations.

BACKGROUND: SARS-CoV-2 has triggered a pandemic that is now claiming many lives. Several studies have investigated cellular immune responses in COVID-19-infected patients during disease but little is known regarding a possible protracted impact of COVID-19 on the adaptive and innate immune system in COVID-19 convalescent patients. METHODS: We used multiparametric flow cytometry to analyze whole peripheral blood samples and determined SARS-CoV-2-specific antibody levels against the S-protein, its RBD-subunit, and viral nucleocapsid in a cohort of COVID-19 convalescent patients who had mild disease ~10 weeks after infection (n = 109) and healthy control subjects (n = 98). Furthermore, we correlated immunological changes with clinical and demographic parameters. RESULTS: Even ten weeks after disease COVID-19 convalescent patients had fewer neutrophils, while their cytotoxic CD8+ T cells were activated, reflected as higher HLA-DR and CD38 expression. Multiparametric regression analyses showed that in COVID-19-infected patients both CD3+ CD4+ and CD3+ CD8+ effector memory cells were higher, while CD25+ Foxp3+ T regulatory cells were lower. In addition, both transitional B cell and plasmablast levels were significantly elevated in COVID-19-infected patients. Fever (duration, level) correlated with numbers of central memory CD4+ T cells and anti-S and anti-RBD, but not anti-NC antibody levels. Moreover, a "young immunological age" as determined by numbers of CD3+ CD45RA+ CD62L+ CD31+ recent thymic emigrants was associated with a loss of sense of taste and/or smell. CONCLUSION: Acute SARS-CoV-2 infection leaves protracted beneficial (ie, activation of T cells) and potentially harmful (ie, reduction of neutrophils) imprints in the cellular immune system in addition to induction of specific antibody responses.

Extracorporeal photopheresis as second-line therapy for patients with acute graft-versus-host disease: does the number of cells treated matter?

BACKGROUND: Extracorporeal photopheresis (ECP) has demonstrated efficacy as second-line treatment for steroid-refractory (SR) acute graft-versus-host disease (aGVHD). The aim of our study was to analyze whether the amount of ECP-treated cells in patients with SR, aGVHD has an impact on response at 1 month. STUDY DESIGN AND METHODS: Data on white blood cells, lymphocytes, monocytes, mononuclear cells, and neutrophils, including absolute counts and counts per kilogram of body weight in ECP products from patients with aGVHD, were collected. For each cell population, the median dose per single ECP and the cumulative doses collected during the first week and the first month of treatment were compared with the response to ECP. RESULTS: In total, 99 patients underwent 1215 ECP procedures. Overall response was defined as a complete response if all signs of aGVHD resolved or a partial response if greater than 50% resolution was reached without other, additional immunosuppression. An overall response was obtained by 75% of patients, including 53% complete responses. Univariate analysis showed a correlation of lymphocytes and mononuclear cells/kg body weight for a single procedure and overall response. In logistic regression analysis, no tested variable had an influence on response. In receiver operating characteristic curve analysis, cutoffs of 8.4 × 106 /kg body weight lymphocytes and 13.9 × 106 /kg body weight mononuclear cells were associated with an overall response to ECP at 1 month with 75% sensitivity. CONCLUSION: Our results in patients with steroid-refractory aGVHD confirm that response rates to ECP are high and that certain cutoff values for lymphocytes and mononuclear cells/kg body weight in each individual procedure can predict an overall response to ECP at 1 month.