Function of polymorphonuclear neutrophilic leucocytes. Comparison of leucocytes from blood and exudate in healthy volunteers
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Abstract:
The function of polymorphonuclear neutrophils from blood (B-PMN) and from exudates (E-PMN) was studied in healthy volunteers. The E-PMNs were isolated from skin windows with chambers and the chemotactic, phagocytic and Nitro Blue Tetrazolium (NBT) reducing activity measured and compared to that of simultaneously obtained B-PMNs. The chemotactic and random migration of E-PMNs in Boyden chambers measured by the leading front and by the chemotactic index were reduced compared with B-PMNs (p less than 0.01). Serum independent phagocytosis of paraffin oil emulsions was significantly increased (p less than 0.01) by E-PMNs after 12, 24 and 48 hours and not correlated to the function of B-PMNs. Opsonization with autologous serum increased the phagocytosis by both E-PMNs and B-PMNs, but mainly the latter. The NBT reduction by E-PMNs was increased (p less than 0.01) and positively correlated to the NBT reduction by resting B-PMNs. In contrast, there was no difference in NBT reduction between phagocytosing E-PMNs and B-PMNs. Mobilization of PMNs to an inflammatory focus in healthy subjects induces marked changes in the function, and B-PMN function cannot always be assumed to reflect the function of PMNs from inflammatory sites.
Insights
Neutrophil function changes upon migration to inflammatory sites. Blood neutrophils (B-PMN) differ significantly from exudate neutrophils (E-PMN) in chemotaxis, phagocytosis, and NBT reduction, highlighting distinct roles in inflammation.
Area of Science:
- Immunology
- Cell Biology
- Inflammation Research
Background:
- Polymorphonuclear neutrophils (PMNs) are crucial immune cells involved in inflammatory responses.
- Understanding PMN function is vital for diagnosing and treating inflammatory conditions.
- Distinct PMN populations may exist with specialized functions.
Purpose of the Study:
- To compare the functional characteristics of blood (B-PMN) and exudate (E-PMN) neutrophils in healthy volunteers.
- To investigate chemotaxis, phagocytosis, and Nitro Blue Tetrazolium (NBT) reducing activity of E-PMNs versus B-PMNs.
- To determine if B-PMN function accurately reflects E-PMN function at inflammatory sites.
Main Methods:
- Isolation of E-PMNs from skin window chambers in healthy volunteers.
- Simultaneous isolation of B-PMNs from the blood of the same volunteers.
- Assessment of chemotactic migration using Boyden chambers (leading front, chemotactic index).
- Measurement of serum-independent and serum-opsonized phagocytosis of paraffin oil emulsions.
- Evaluation of NBT reducing activity in resting and phagocytosing neutrophils.
Main Results:
- E-PMNs exhibited significantly reduced chemotactic and random migration compared to B-PMNs (p < 0.01).
- Serum-independent phagocytosis was significantly increased by E-PMNs at 12, 24, and 48 hours (p < 0.01).
- Opsonization enhanced phagocytosis primarily in B-PMNs.
- NBT reduction by resting E-PMNs was increased and correlated with B-PMNs (p < 0.01), but no difference was observed during phagocytosis.
- PMN mobilization to inflammation induces significant functional changes.
Conclusions:
- Mobilization to an inflammatory focus induces marked functional alterations in neutrophils.
- The function of blood neutrophils (B-PMN) cannot be reliably assumed to represent the function of neutrophils at inflammatory sites (E-PMN).
- E-PMNs display enhanced phagocytic capacity and altered migratory and NBT reducing activities compared to B-PMNs.