TISSUE-LEVELS OF HISTAMINE, PAF-ACETHER AND LYSOPAF-ACETHER IN CARRAGEENAN-INDUCED GRANULOMA IN RATS

The tissue concentrations of several inflammatory mediators were deter mined from day 0 to day 60 in granuloma induced in rats (n = 105) by i njection of carrageenan in the fascia of the latissimus dorsi muscle. Noncollagen proteins (NCP) and the number of polymorphonuclear leukocy tes (PMN) and mast cells were also assessed. In comparison with the ti ssue at time 0, we noted in the inflamed tissue (at 4 h) an increase i n total proteins (4.0 +/- 3.0 vs. 84 +/- 12.0%, mean +/- SEM) and PMN (0.0 +/- 0.0 vs. 43.3 +/- 13.4%), and a fall in histamine concentratio n (from 30.0 +/- 9.0 to 9.0 +/- 4.0 ng/ml). A partial disappearence of mast cells and an increase of PAF-acether (PAF) levels (1.0 +/- 1.0 v s. 30.0 +/- 22.0 ng/ml) was noted at 16 h, whereas lysopaf remained un changed (3.7 +/- 4.0 vs. 3.5 +/- 1.0 ng/ml). During evolution towards chronic inflammation (day 10-60), NCP decreased, PMN disappeared and m ast cells reapeared; the histamine level rose to 11.0 +/- 2.0 mg/ml, t hus not reaching back baseline values, Lysopaf rose to 7.1 +/- 12.2 ng /ml and PAF levels increased further to reach 240.0 +/- 153.0 ng/ml at day 10. This study suggests that PAF may contribute to the acute phas e of an inflammatory state such as the carrageenan-induced granuloma a nd that it is also present during the chronic process.