László Gopcsa

Objectives: Uncontrolled thromboinflammation plays an important role in the pathogenesis of coronavirus disease (COVID-19) caused by SARS-CoV-2 virus. Complement was implicated as key contributor to this process, therefore we hypothesized that markers of the complement profile, indicative for the activation state of the system, may be related to the severity and mortality of COVID-19. Methods: In this prospective cohort study samples of 102 hospitalized and 26 outpatients with PCR-confirmed COVID-19 were analyzed. Primary outcome was in-hospital, COVID-19 related mortality, and secondary outcome was COVID-19 severity as assessed by the WHO ordinal scale. Complement activity of alternative and classical pathways, its factors, regulators, and activation products were measured by hemolytic titration, turbidimetry, or enzyme-immunoassays. Clinical covariates and markers of inflammation were extracted from hospital records. Results: Increased complement activation was characteristic for hospitalized COVID-19 patients. Complement activation was significantly associated with markers of inflammation, such as interleukin-6, C-reactive protein, and ferritin. Twenty-five patients died during hospital stay due to COVID-19 related illness. Patients with uncontrolled complement activation leading to consumption of C3 and decrease of complement activity were more likely to die, than those who had complement activation without consumption. Cox models identified anaphylatoxin C3a, and C3 overactivation and consumption (ratio of C3a/C3) as predictors of in-hospital mortality [HR of 3.63 (1.55-8.45, 95% CI) and 6.1 (2.1-17.8), respectively]. Conclusion: Increased complement activation is associated with advanced disease severity of COVID-19. Patients with SARS-CoV-2 infection are more likely to die when the disease is accompanied by overactivation and consumption of C3. These results may provide observational evidence and further support to studies on complement inhibitory drugs for the treatment of COVID-19.

Central nervous system involvement is a rare complication of multiple myeloma with extremely poor prognosis as it usually fails to respond to therapy. We present 13 cases diagnosed at two centers in Budapest and review the current literature. The majority of our cases presented with high-risk features initially; two had plasma cell leukemia. Repeated genetic tests showed clonal evolution in 3 cases. Treatments varied according to the era, and efficacy was poor as generally reported in the literature. Only one patient is currently alive, with 3-month follow-up, and the patient responded to daratumumab-based treatment. Recent case reports show promising effectivity of pomalidomide and marizomib.

Plasmacytoid dendritic cells (pDCs) are professional type I interferon (IFN)-producing cells that play an essential role in antiviral immunity. In many cell types, detection of intracellular pathogens is mostly dependent on endosomal Toll-like receptors (TLRs) and cytosolic sensors, such as retinoic acid-inducible gene I (RIG-I). However, the possible interplay between these two systems has not yet been elucidated. Here we aimed to study the collaboration of endosomal TLRs and RIG-I in primary human pDCs. We found that under steady-state conditions, pDCs express RIG-I at very low level, but the expression of this receptor is rapidly and dramatically upregulated upon stimulation by the TLR7 ligand imiquimod or the TLR9 ligand type A CpG. We also demonstrated that pDCs are able to sense and respond to 5'-triphosphate double-stranded RNA (5'-ppp-dsRNA) only following activation by endosomal TLRs. Experiments on primary pDCs with functionally blocked IFN-α/β receptor 1 (IFNAR1) and those on human pDC leukemia (pDC-L) cells defective in type I IFN secretion indicated that the upregulation of RIG-I expression in pDCs upon stimulation by endosomal TLR occurs in a type I IFN-independent manner. Selective phosphorylation of signal transducer and activator of transcription 1 (STAT1) on tyrosine 701 could be identified as an early signaling event in this process. Our results show that in contrast to many other cell types, where RIG-I expression is induced by type I IFN, in pDCs a disparate mechanism is responsible for the upregulation of RIG-I. Our findings also indicate that along with autophagy, an additional mechanism is operating in pDCs to promote the detection of replicating viruses.

OBJECTIVES: Accumulating evidence suggests that non-T, non-B cell CD4+CD56+ neoplasms with lymphoblastic morphology include clinically and immunophenotypically diverse entities. Although their cells of origin or classification are still controversial several entities clearly represent a distinct type of neoplasms that are clinically aggressive. METHODS: In this work we present the immunophenotypic and genotypic features of bone marrow (BM), peripheral blood (PB), lymph node and skin lymphocytes from a patient diagnosed as plasmacytoid dendritic cell leukemia involving the skin, BM, PB, lymph nodes, liver and spleen. For determination of immunophenotypic characteristics of malignant plasmacytoid dendritic cells 73 monoclonal antibodies detecting lineage markers, chemokine receptors, cytokine receptors, activation, and co-stimulatory molecules were used. RESULTS AND CONCLUSION: The malignant cells proved to express CD4+, CD56+ lineage negative leukemia phenotype characteristically positive for CD36, CD38, CD40, CD45, CD45RA, CD68, CD123, CD184, HLA-DR, BDCA2, and granzyme-B corresponding to the preplasmacytoid dendritic cell developmental stage. The presence of CD11a/CD18, CD84, CD91, CD95, alphavbeta5, CDw197, and the absence of CD52 and CD133 in this case can be regarded as additional features of malignant cells. Completing the immunophenotypes with multidrug resistance function can provide additional information for characterizing pDC leukemia.