Enhanced vascular permeability and haemorrhage-inducing activity of rabbit C5ades arg: probable role of polymorphonuclear leucocyte lysosomes
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Abstract:
We previously reported that the injection into rabbit skin of rabbit zymosan-activated plasma (ZAP) induces marked polymorphonuclear leucocyte (PMN) infiltration, a transient increase in vascular permeability (1 hr) and prolonged red blood cells extravasation lasting at least 10 hr. Here we describe the fractionation of ZAP to identify the factor(s) responsible for these effects. On CM Sephadex G-25 chromatography, the majority of the leucocyte-attracting, permeability-enhancing and haemorrhage-inducing activities eluted in the high-salt fractions (0 . 6 M ammonium formate, 1 M NaCl pH 5 . 0), suggesting that this is a very basic molecule(s). Furthermore, the three activities eluted in the same fraction on Sephadex G-100, with an apparent molecular weight of 14,000--17,000 daltons. These observations, and the previously described requirement for C5 in the plasma, suggest that C5ades arg is the active factor. Experiments performed in neutropenic rabbits indicated that PMN are required for both the increase in permeability and red cell extravasation. Ultrastructural studies showed extensive degenerative changes in the infiltrating PMNs evident even in 1--2-hr lesions. These ranged from 'watery' cytoplasm, loss of glycogen and cell membrane to segregation and extensive extracellular release of lysosomes. It is postulated that C5ades arg-induced chemotaxis and metabolic perturbations contribute to this rapid degeneration of the PMNs, and that the release of lysosomes from these cells results in progressive vascular injury.
Insights
Zymosan-activated plasma (ZAP) contains a factor, likely C5a, that attracts polymorphonuclear leukocytes (PMNs). This factor causes PMN degeneration and vascular injury, leading to increased permeability and red blood cell extravasation in rabbit skin.
Area of Science:
- Immunology
- Vascular Biology
- Complement System
Background:
- Zymosan-activated plasma (ZAP) induces polymorphonuclear leukocyte (PMN) infiltration, vascular permeability, and red blood cell extravasation in rabbit skin.
- The specific factor(s) within ZAP responsible for these inflammatory responses were not previously identified.
Purpose of the Study:
- To fractionate ZAP and identify the active component(s) mediating PMN infiltration, vascular permeability, and hemorrhage.
- To elucidate the role of PMNs in ZAP-induced vascular injury.
Main Methods:
- Fractionation of ZAP using CM Sephadex G-25 and Sephadex G-100 chromatography.
- Assay of fractions for leukocyte-attracting, permeability-enhancing, and hemorrhage-inducing activities.
- Experiments in neutropenic rabbits to assess the role of PMNs.
- Ultrastructural analysis of infiltrating PMNs.
Main Results:
- A basic molecule with a molecular weight of 14,000–17,000 daltons was identified as responsible for all three activities.
- The active factor co-eluted with C5-dependent activity, suggesting it is C5ades arg.
- PMNs were essential for increased vascular permeability and red blood cell extravasation.
- Infiltrating PMNs exhibited rapid degenerative changes, including lysosomal release.
Conclusions:
- C5ades arg is the primary factor in ZAP responsible for PMN recruitment and subsequent vascular injury.
- PMN degeneration and lysosomal release are critical mechanisms contributing to ZAP-induced progressive vascular damage.
- The findings highlight the role of the complement system in acute inflammatory responses and tissue injury.