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The initial lag in phagocytic rate by macrophages in monolayer is related to particle encounters and binding
Abstract:
Several investigators have described an initial "lag" in the phagocytic rates of macrophages in assay systems involving these phagocytes in monolayer. In the present study, we determined whether this apparent lag in phagocytic activity is due to a delay in the onset of macrophage phagocytic function per se, or if the lag phase can be explained by a relative lack of particle availability in terms of particle encounters and binding during the early phases of a phagocytic assay. Studies involving the pre-binding of opsonized erythrocytes to macrophages revealed that the lag in phagocytosis usually seen in assay systems involving macrophages in monolayer is related to particle availability.
Insights
The initial lag in macrophage phagocytosis is not due to delayed cell function, but rather limited particle availability during early assay phases. Pre-binding particles resolves this observed lag in phagocytic activity.
Area of Science:
- Immunology
- Cell Biology
Background:
- Macrophages exhibit an initial lag in phagocytic rates in standard monolayer assays.
- The cause of this lag has been debated, with possibilities including delayed cell activation or limited particle interaction.
Purpose of the Study:
- To investigate the underlying cause of the initial lag in macrophage phagocytosis.
- To differentiate between delayed macrophage function and particle availability as the reason for the observed lag.
Main Methods:
- Utilized phagocytic assays with macrophages in monolayer.
- Employed pre-binding of opsonized erythrocytes to macrophages to control particle availability.
- Monitored phagocytic rates over time.
Main Results:
- The apparent lag in phagocytosis is primarily attributed to limited particle encounters and binding in early assay stages.
- Pre-binding of particles to macrophages eliminated the characteristic lag phase.
- Macrophage phagocytic function itself does not appear to be delayed.
Conclusions:
- The initial lag in macrophage phagocytosis assays is a phenomenon related to particle availability, not a delay in the cells' intrinsic phagocytic capacity.
- Optimizing particle availability can overcome the observed lag in phagocytic assays.