Immune cell kinetics and antibody response inCOVID‐19 patients with low‐count monoclonal B‐cell lymphocytosis

Abstract

AbstractLow‐count monoclonal B‐cell lymphocytosis (MBLlo) has been associated with an underlying immunodeficiency and has recently emerged as a new risk factor for severe COVID‐19. Here, we investigated the kinetics of immune cell and antibody responses in blood during COVID‐19 of MBLloversus non‐MBL patients. For this study, we analyzed the kinetics of immune cells in blood of 336 COVID‐19 patients (74 MBLloand 262 non‐MBL), who had not been vaccinated against SARS‐CoV‐2, over a period of 43 weeks since the onset of infection, using high‐sensitivity flow cytometry. Plasma levels of anti‐SARS‐CoV‐2 antibodies were measured in parallel by ELISA. Overall, early after the onset of symptoms, MBLloCOVID‐19 patients showed increased neutrophil, monocyte, and particularly, plasma cell (PC) counts, whereas eosinophil, dendritic cell, basophil, and lymphocyte counts were markedly decreased in blood of a variable percentage of samples, and with a tendency toward normal levels from week +5 of infection onward. Compared with non‐MBL patients, MBLloCOVID‐19 patients presented higher neutrophil counts, together with decreased pre‐GC B‐cell, dendritic cell, and innate‐like T‐cell counts. Higher PC levels, together with a delayed PC peak and greater plasma levels of anti‐SARS‐CoV‐2‐specific antibodies (at week +2 to week +4) were also observed in MBLlopatients. In summary, MBLloCOVID‐19 patients share immune profiles previously described for patients with severe SARS‐CoV‐2 infection, associated with a delayed but more pronounced PC and antibody humoral response once compared with non‐MBL patients.