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Polymorphonuclear leukocyte accumulation in inflammatory dermal sites as measured by 51Cr-labeled cells and
Abstract:
Two methods for quantitating polymorphonuclear leukocyte (PMN) accumulation in inflammatory skin lesions were studied. The lesions were produced in rats by intradermal injections of different dilutions of zymosan-activated plasma (ZAP). PMN accumulation in the skin lesions was estimated by determination of (1) homologous 51Cr-labeled PMNs and (2) activity of myeloperoxidase (MPO) in the tissue sample. 125I-labeled human serum albumin was used for measurement of albumin extravasation. The [51Cr]PMN content and MPO activity in the skin lesions were both proportional to the concentration of ZAP injected. The correlation coefficient (r) between the two methods of measuring PMN accumulation in the inflammatory skin lesions was calculated to be 0.81 +/- 0.13 (mean +/- SD, N = 8). The proportionality of the PMN accumulation to the different dilutions of injected ZAP, as measured both by [51Cr]PMN and by MPO activity, and the correlation of the two methods to each other, suggest that these two methods are reliable for measuring PMN accumulation in vivo. The inflammatory reaction also included albumin extravasation, which reached a relatively high level already at the lowest concentration of injected ZAP and did not seem to parallel PMN accumulation.
Insights
Two reliable methods for quantifying polymorphonuclear leukocyte (PMN) accumulation in skin inflammation were validated using zymosan-activated plasma (ZAP) in rats. Both 51Cr-labeled PMNs and myeloperoxidase (MPO) activity accurately measured PMN influx.
Area of Science:
- Immunology
- Inflammation Research
- Biomedical Science
Background:
- Polymorphonuclear leukocytes (PMNs) are crucial in inflammatory responses.
- Accurate quantification of PMN infiltration is essential for studying inflammation.
- Zymosan-activated plasma (ZAP) is a common inducer of experimental skin inflammation.
Purpose of the Study:
- To evaluate and compare two methods for quantifying PMN accumulation in inflammatory skin lesions.
- To assess the reliability of these methods in an in vivo model.
Main Methods:
- Experimental inflammatory skin lesions were induced in rats using intradermal injections of varying dilutions of ZAP.
- PMN accumulation was measured using homologous 51Cr-labeled PMNs and myeloperoxidase (MPO) activity.
- Albumin extravasation was assessed using 125I-labeled human serum albumin.
Main Results:
- Both 51Cr-labeled PMN content and MPO activity in skin lesions were directly proportional to ZAP concentration.
- A high correlation (r = 0.81 +/- 0.13) was observed between the 51Cr-PMN and MPO activity measurements.
- Albumin extravasation occurred early and did not consistently parallel PMN accumulation.
Conclusions:
- Both 51Cr-labeled PMN quantification and MPO activity are reliable methods for measuring PMN accumulation in vivo.
- These methods provide accurate and reproducible assessments of inflammatory cell infiltration.
- The study highlights the distinct kinetics of PMN accumulation and albumin extravasation during inflammation.
