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What are reactive monocytes?
Monocytes are the largest cells amongst the white blood cells and are extremely important for the body’s immune response. Deriving from the hematopoietic stem cell, mature monocytes circulate for one to three days in the peripheral blood until they travel into the tissue. Arrived there, they differentiate into macrophages and dendritic cells and hence play a key role in the innate immune response.
When a host’s immune system is triggered by invading pathogens, immune cells like monocytes are activated. When reactive, monocytes can eliminate pathogens by phagocytosis, release reactive oxygen species (ROS), produce proinflammatory cytokines and modulate the T cell immune response of the adaptive immune response.
How to use the parameter?
These signs of activation are reflected in the cells’ appearance and can be measured with fluorescence flow cytometry in the WDF channel on XN-Series analysers. The number of reactive monocytes in the peripheral blood are counted and output as RE-MONO* (reactive monocytes) parameters.
In comparison to resting cells, reactive monocytes are characterised by both increased nucleic acid content and increased cell granularity resulting from enhanced metabolic activity and vacuolisation respectively. Hence, the side fluorescence signal (SFL) and the side scattered light signal (SSC) can be enhanced and the cell population appears in the WDF scattergram higher than resting cells.
RE-MONO provides an additional information on the activation status of the host’s immune system. Moreover, it had been shown previously that different pathogen species evoke different patterns in blood cell number and phenotype when triggering the host’s immune response (Prodjosoewojo S et al. 2019). This is reflected in pathogen-specific degrees of monocyte activation and visible in the position of the reactive monocyte population.
Reference: Prodjosoewojo S et al. 2019, PLoS Negl Trop Dis 13(3). Free online.
*Research and service parameters are for research use only. Any in vitro diagnostics purpose has not been established by the manufacturer. Therefore, internal validation at the user’s facilities with appropriate samples will be required before using any information generated to establish a diagnosis or decide on a therapeutic treatment. The information generated should never be the sole determinant for taking medical decisions.