In sickle cell anemia, red blood cells have a predominant role in the enhancement of phagocytic activity by mast cells, but in polycythemia vera, both cell types contribute to this phenomenon
Stress erythropoiesis (SE) occurs when the physiological process of erythropoiesis is insufficient to fulfill the required production of functional red blood cells (RBCs), resulting in heightened activity in extramedullary sites. SE is present in disorders such as sickle cell anemia (SCA) and polycythemia vera (PV), hence affecting the functioning of red blood cells (RBCs).
The objective of this study, presented as a poster at the 65th American Society of Hematology Annual Meeting and Exposition, was to determine whether the increased phagocytic activity observed in monocytes (MCs) of these individuals is affected by changes in MC phenotype or red blood cell (RBC) features, and also to investigate the consequences related to iron metabolism following phagocytosis.
Mononuclear cells (MCs) derived from peripheral blood were subjected to incubation with labeled red blood cells (RBCs), facilitating the process of phagocytosis. The implications of iron metabolism were examined using flow cytometry analysis using anti-intracellular heme-oxygenase-1 (HO-1) and anti-membrane ferroportin (FPN) antibodies. The statistical analysis utilized the paired Student t-test with a significance level of P<0.05.
High Phagocytic Capacity in Sickle Cell Anemia
Mononuclear cells (MCs) from both SCA patients and healthy individuals, upon exposure to SCA RBCs, demonstrated a heightened phagocytic capacity in comparison to the same cells exposed to RBCs from healthy controls (mean corpuscular hemoglobin concentration (MCHC 22.9±8 vs 9.4±1.1, **P=0,0099; MCSCA 33.6±11.4 vs 16.4±11, **P=0,0054; respectively)
Enhanced Phagocytosis in Polycythemia Vera and Healthy Control Mononuclear Cells With Exposure to Polycythemia Vera Red Blood Cells
The phagocytic activity of MCs derived from individuals with polycythemia vera (PV) and healthy controls (HC) when exposed to PV RBCs revealed that the presence of PV RBCs led to a significant increase in phagocytic activity compared to the presence of HC RBCs (MCHC 9.3±4.4 vs 2.8±4.7, **P=0.0065; MCPV 21.3±6.1 vs 11±6.8, *P=0.0146; respectively).
Sickle Cell Anemia Mononuclear Cells Exhibited a Phagocytic Pattern Similar to That of Healthy Control Mononuclear Cells
The SCA MCs displayed a phagocytic pattern that was comparable to the HC MCs (P=0.0699); however, the PV MCs revealed considerably greater phagocytic capability in comparison to the HC MCs (**P=0.0022). Moreover, across all the studied groups, the MCs that engaged in phagocytosis exhibited increased levels of both HO-1 and ferroportin FPN, underscoring their pivotal involvement in this process.
Source:
Marina, D. B. (2023, December 10). Erythrophagocytosis mediated by circulating monocytes is induced by distinct mechanisms depending on the disease. https://ash.confex.com/ash/2023/webprogram/Paper189370.html
