Lymphopenia is a frequent hematological manifestation, associated with a severe course of COVID-19, with an insufficiently understood pathogenesis. We present molecular genetic immunohistochemical, and electron microscopic data on SARS-CoV-2 dissemination and viral load (VL) in lungs, mediastinum lymph nodes, and the spleen of 36 patients who died from COVID-19. Lymphopenia <1 × 10⁹/L was observed in 23 of 36 (63.8%) patients. In 12 of 36 cases (33%) SARS-CoV-2 was found in lung tissues only with a median VL of 239 copies (range 18–1952) SARS-CoV-2 cDNA per 100 copies of ABL1. Histomorphological changes corresponding to bronchopneumonia and the proliferative phase of DAD were observed in these cases. SARS-CoV-2 dissemination into the lungs, lymph nodes, and spleen was detected in 23 of 36 patients (58.4%) and was associated with the exudative phase of DAD in most of these cases. The median VL in the lungs was 12,116 copies (range 810–250281), lymph nodes—832 copies (range 96–11586), and spleen—71.5 copies (range 0–2899). SARS-CoV-2 in all cases belonged to the 19A strain. A immunohistochemical study revealed SARS-CoV-2 proteins in pneumocytes, alveolar macrophages, and bronchiolar epithelial cells in lung tissue, sinus histiocytes of lymph nodes, as well as cells of the Billroth pulp cords and spleen capsule. SARS-CoV-2 particles were detected by transmission electron microscopy in the cytoplasm of the endothelial cell, macrophages, and lymphocytes. The infection of lymphocytes with SARS-CoV-2 that we discovered for the first time may indicate a possible link between lymphopenia and SARS-CoV-2-mediated cytotoxic effect.

Multi-organ failure is one of the common causes of fatal outcome in COVID-19 patients. However, the pathogenetic association of the SARS-CoV-2 viral load (VL) level with fatal dysfunctions of the lungs, liver, kidneys, heart, spleen and brain, as well as with the risk of death in COVID-19 patients remains poorly understood. SARS-CoV-2 VL in the lungs, heart, liver, kidneys, brain, spleen and lymph nodes have been measured by RT qPCR using the following formula: N^SARS-CoV−2/N^{ABL1 ×} 100. Dissemination of SARS-CoV-2 in 30.5% of cases was mono-organ, and in 63.9% of cases, it was multi-organ. The average SARS-CoV-2 VL in the exudative phase of diffuse alveolar damage (DAD) was 60 times higher than in the proliferative phase. The SARS-CoV-2 VL in the lungs ranged from 0 to 250,281 copies. The “pulmonary factors” of SARS-CoV-2 multi-organ dissemination are the high level of SARS-CoV-2 VL (≥4909) and the exudative phase of DAD. The frequency of SARS-CoV-2 dissemination to lymph nodes was 86.9%, heart–56.5%, spleen–52.2%, liver–47.8%, kidney–26%, and brain–13%. We found no link between the SARS-CoV-2 VL level in the liver, kidneys, and heart and the serum level of CPK, LDH, ALP, ALT, AST and Cr of COVID-19 patients. Isolated detection of SARS-CoV-2 RNA in the myocardium of COVID-19 patients who died from heart failure is possible. The pathogenesis of COVID-19-associated multi-organ failure requires further research in a larger cohort of patients.

JAK2 (Janus kinase 2) V617F, CALR (Calreticulin) exon 9, and MPL (receptor for thrombopoietin) exon 10 mutations are associated with the vast majority of Ph-negative chronic myeloproliferative neoplasms (MPNs). These mutations affect sequential stages of proliferative signal transduction and therefore, after the emergence of one type of mutation, other types should not have any selective advantages for clonal expansion. However, simultaneous findings of these mutations have been reported by different investigators in up to 10% of MPN cases. Our study includes DNA samples from 1958 patients with clinical evidence of MPN, admitted to the National Research Center for Hematology for genetic analysis between 2016 and 2019. In 315 of 1402 cases (22.6%), CALR mutations were detected. In 23 of these 315 cases (7.3%), the JAK2 V617F mutation was found in addition to the CALR mutation. In 16 from 24 (69.6%) cases, with combined CALR and JAK2 mutations, V617F allele burden was lower than 1%. A combination of JAK2 V617F with MPL W515L/K was also observed in 1 out of 1348 cases, only. JAK2 allele burden in this case was also lower than 1%. Additional mutations may coexist over the low background of JAK2 V617F allele. Therefore, in cases of detecting MPNs with a low allelic load JAK2 V617F, it may be advisable to search for other molecular markers, primarily mutations in exon 9 of CALR. The load of the combined mutations measured at different time points may indicate that, at least in some cases, these mutations could be represented by different clones of malignant cells.

Introduction. The advent of tyrosine kinase inhibitors (TKIs) in clinical practice drastically improved prognosis in patients with chronic myeloid leukaemia (CML). Adverse events of the TKI therapy and its high financial burden warrant the trend to gradually abandon this treatment.Aim. To assess the results of CML patient monitoring after the withdrawal of TKI therapy.Patients and methods. This prospective study included 98 chronic phase CML patients satisfying the criteria: any receiving of TKI therapy for ≥3 years; deep molecular response (DMR, BCR-ABL ≤ 0.01 % IS) during ≥ 2 years. The withdrawal was followed by quantitative BCR-ABL estimation performed monthly for the first 6 months of the survey, bimonthly for 1 year and every 3 months from the second year onwards. Therapy was resumed at a loss of major molecular response (MMR, BCR-ABL ≥ 0.1 % IS).Results. The MMR loss upon the TKI withdrawal was observed in 48 (49 %) patients. Survival without MMR loss was 52 % past 24 months since withdrawal, with a median of 35 months (23–52). The duration of therapy, MR and the MR depth at the time of withdrawal significantly correlated with a conserved post-therapy MMR. Gender, age, a Sokal risk group, type and line of TKI therapy at withdrawal, and imatinib resistance in history were not observed to significantly impact molecular relapse-free remission. MMR was recovered in all 48 patients with TKI therapy resumed in molecular relapse. In 65 % of the patients, adverse therapy events observed during treatment completely resolved by 6 months of post-therapy monitoring. Musculoskeletal pain (withdrawal syndrome, WS) was reported in 42 % patients in the post-therapeutic period, which did not lead to TKI resumption. The WS development correlated with an elder age and longer therapy prior to withdrawal.Conclusion. Molecular relapse-free survival in CML patients with treatment-free remission (TFR) is comparable to other published evidence. Monitoring safety during TFR is attested by the lack of disease progression and MMR recovery upon TKI resumption in all patients.

Chronic myeloid leukemia (CML) is a myeloproliferative disease, caused by BCR/ABL protein with high tyrosine kinase activity. Since 2001, CML has been effectively treated with tyrosine kinase inhib...

Цель исследования: иммуногистохимическая и электронно-микроскопическая визуализация коронавируса SARS-CoV-2 в тканях легких, лимфатических узлов и почек пациентов, умерших от COVID-19. Материалы и методы. Для иммуногистохимических исследований в качестве материала использованы срезы фиксированных в формалине и заключенных в парафин тканей легких, лимфатических узлов и почек пациентов, умерших от COVID-19. Количественная оценка уровня вирусной нагрузки SARS-CoV-2 проведена с использованием оригинального способа кПЦР РВ и рассчитана по формуле: число копий SARS-CoV-2/число копий ABL1 х 100, выражена отношением истинного числа копий кДНК SARS-CoV-2 на 100 копий кДНК гена ABL1. Для морфологических исследований взяты нативные образцы тканей легких, лимфатических узлов и почек. Результаты. При иммуногистохимическом и электронно-микроскопическом исследовании частицы коронавируса SARS-CoV-2 были обнаружены в цитоплазме эндотелиальных клеток аэрогематического барьера легких, сосудистого клубочка почек, в цитоплазме макрофагов лимфатического узла, а также в цитоплазме лимфоцитов в просвете капилляров легких.