Abstract
Biochemical activities of the human platelet vascular permeability factor (HVPF) and platelet-derived growth factor (PDGF) were studied on rabbit skin and on in vitro cell culture in the present experiments. HVPF was extracted from human platelet α-granules, while PDGF was obtained from the α-granule lysate.Commercial PDGF was used as a control of the lysate. Vascular permeability was estimated by 125I-albumin or chromatoscanner method and its effects were observed by means of electron microscopy. Immediately after injection, all of the factors induced vascular permeability response followed by inflammatory cell infiltration to almost the same extent. At 1 hour, the injected skin site showed an increase of radio activity and bluing. Growth activity was determined by either counting the cell number or estimating the uptake of 3H-thymidine by K 562, Balb/c and NIH 3T3 fibroblast in the culture well. Following the addition of either factors, the cell had proliferated and the uptake of 3H-thymidine was increased in degree. Both HVPF and lysate were heat-stable at 100°C for 10 minutes, but were inactivated by pepsin or 2-mercaptoethanol.
In conclusion, HVPF and PDGF including the commercial one are quite similar in respect of the biological nature. Therefore, it is suggested that the factors play a role not only in the inflammation, but also in the repair of tissue injury.
