ABSTRACT
Impaired immune responses have been hypothesised to be a possible trigger of unfavourable outcomes in coronavirus disease 2019 (COVID-19). We aimed to characterise IgM memory B cells in patients with COVID-19 admitted to an internal medicine ward in Northern Italy. Overall, 66 COVID-19 patients (mean age 74 ± 16.6 years; 29 females) were enrolled. Three patients (4.5%; 1 female) had been splenectomised and were excluded from further analyses. Fifty-five patients (87.3%) had IgM memory B cell depletion, and 18 (28.6%) died during hospitalisation (cumulative incidence rate 9.26/100 person-week; 5.8-14.7 95% CI). All patients who died had IgM memory B cell depletion. A superimposed infection was found in 6 patients (9.5%), all of them having IgM memory B cell depletion (cumulative incidence rate 3.08/100 person-week; 1.3-6.8 95% CI). At bivariable analyses, older age, sex, number of comorbidities, and peripheral blood lymphocyte count < 1500/µl were not correlated with IgM memory B cell depletion. A discrete-to-marked reduction of the B-cell compartment was also noticed in autoptic spleen specimens of two COVID-19 patients. We conclude that IgM memory B cells are commonly depleted in COVID-19 patients and this correlates with increased mortality and superimposed infections.
Subject(s)
B-Lymphocytes/cytology , COVID-19/mortality , Hospital Mortality , Immunologic Memory/immunology , Lymphocyte Depletion , Adult , Aged , Aged, 80 and over , B-Lymphocyte Subsets/cytology , B-Lymphocyte Subsets/immunology , B-Lymphocytes/immunology , COVID-19/pathology , Female , Humans , Immunoglobulin M/blood , Longitudinal Studies , Lymphocyte Count , Male , Middle Aged , Prospective Studies , SARS-CoV-2/immunology , Spleen/cytology , Spleen/immunologyABSTRACT
Non-chronic lymphocytic leukemia (non-CLL) clonal B-cell lymphocytosis (CBL) encompasses a heterogeneous group of hematologic disorders that are still poorly understood. To shed light on their biological aspects, we retrospectively analyzed a highly selected series of 28 patients, who had a clonal B-cell population in the peripheral blood and in the bone marrow, without evidence of lymphoma. Extended targeted next-generation sequencing revealed wide molecular heterogeneity with MYD88 (14%), PDE4DIP (14%), BIRC3 (11%), CCND3 (11%), NOTCH1 (11%), and TNFAIP3 (11%) as the most mutated genes. Mutations of MYD88 were "nonclassic" in most cases. Although some genetic lesions were overlapping with indolent lymphomas, mainly splenic B-cell lymphomas of marginal zone origin and splenic diffuse red pulp small B-cell lymphoma, the genetic profile of our non-CLL CBL series seemed to suggest that various pathways could be involved in the pathogenesis of these disorders, not mirroring any specific lymphoma entity. These data better enlighten the molecular characteristics of non-CLL CBL; however, more efforts are needed in order to improve the diagnostic process, prognostication, and clinical management.
Subject(s)
Biomarkers, Tumor , Genetic Heterogeneity , High-Throughput Nucleotide Sequencing , Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis , Leukemia, Lymphocytic, Chronic, B-Cell/genetics , Aged , Alleles , Disease Susceptibility , Female , Gene Expression , Genetic Predisposition to Disease , Humans , Immunoglobulin Heavy Chains/genetics , Immunohistochemistry , Immunophenotyping , Leukemia, Lymphocytic, Chronic, B-Cell/metabolism , Male , Middle Aged , MutationSubject(s)
Betacoronavirus , Coronavirus Infections , Pandemics , Pneumonia, Viral , COVID-19 , Endothelial Cells , Humans , SARS-CoV-2ABSTRACT
The somatically acquired V600E mutation of the BRAF gene has been recently described as a molecular marker of hairy cell leukemia (HCL). We developed an allele-specific PCR for this mutation and studied 62 patients with HCL, 1 with HCL variant, 91 with splenic marginal zone lymphoma, 29 with Waldenström macroglobulinemia, and 57 with B-cell chronic lymphoproliferative disorders. The BRAF V600E mutation was detected in all HCL cases and in only 2 of the remaining 178 patients. These 2 subjects had B-cell chronic lymphoproliferative disorders that did not fulfill the diagnostic criteria for HCL. Despite the positive PCR finding, the mutation could not be detected by Sanger sequencing in these 2 cases, suggesting that it was associated with a small subclone. We conclude that the BRAF V600E mutation is present in all patients with HCL and that, in combination with clinical and morphologic features, represents a reliable molecular marker for this condition.
Subject(s)
Leukemia, B-Cell/genetics , Leukemia, Hairy Cell/genetics , Lymphoma, B-Cell/genetics , Point Mutation/genetics , Proto-Oncogene Proteins B-raf/genetics , Adult , DNA, Neoplasm/genetics , Exons/genetics , Female , Humans , Leukemia, B-Cell/pathology , Leukemia, Hairy Cell/pathology , Lymphoma, B-Cell/pathology , Male , Middle Aged , Polymerase Chain ReactionABSTRACT
Bone marrow (BM) examination is essential in the staging of non-Hodgkin's lymphoma (NHL) patients. Few studies have compared BM histologic findings with results of flow cytometric (FC) analysis. We analyzed the incidence and patterns of histologic BM involvement in a series of 753 patients with NHL. For 498 patients, a concurrent FC analysis on BM was available. Histologic involvement was detected at diagnosis in 311/753 (41%) patients. By FC, BM involvement was clearly detected in 150/498 (30%). After excluding 12 cases with equivocal histology, concordance between the two methods was detected in 411 (85%) cases (27% BMB+/FC+; 58% BMB-/FC-), while discordance was present in 75 (15%) (P < 0.001): 58 cases (12%) were BMB+/FC- and 17 (3%) were BMB-/FC+. Discordance was more frequent in FL and in lymphoplasmacytic lymphoma (LPL). These data demonstrate that the two methods are comparable in qualitative assessment of BM involvement in NHL, with the exception of FL and LPL. In FL, diffuse large B-cell lymphoma (DLBCL) and LPL, FC underestimates the extent of infiltrate with respect to histology.
