[IL-6 anti-inflammatory activity in pleural effusion post-coronary artery bypass graft surgery]

The local inflammatory reaction aspects of pleural behaviour post-coronary artery by- pass graft surgery (PCABG) are not completely evident, demanding further study and observation.

To evaluate the behaviour of some cytokines and the possible anti-inflammatory activity of IL-6 (a protein involved in cortisone synthesis) on acute PCA- BG pleural fluid, since this cytokine is usually considered as an acute phase reaction protein associated to high concentrations of TNF-alpha and IL-1 beta in immediate inflammatory reactions.

The concentrations of the TNF-alpha, IL-1 beta, IL-2, IL-6, IL-8, VEGF and TGF-beta cytokines in 16 transudates and 43 exudates in acute PCABS pleural fluid of patients were analysed by the ELISA method 2, 24 and 48 hours after surgery at the Instituto do Coração and Serviço de Pneumologia da USP, Brazil.

While no increase was seen in either TNF-alpha or IL-2 in any of the three tests, IL-1 beta increased after 24 until 48 hours, coinciding with the TGF-beta curve decline which fell from the beginning to reach the transudates levels. IL-8 reminded higher from the beginning and through the two subsequent tests while VEGF levels were elevated from the first test and continued high for the following 24 and 48 hours. IL-6 had high concentrations from the beginning, suggesting an anti-inflammatory activity at the three times of testing.

We conclude that IL-6 seems to play an important anti-inflammatory part which is superior to the anti-inflammatory activity of TGF-beta in PCABG pleural effusions. This performance of IL-6 breaks with the traditional idea of it being a pro-inflammatory acute phase reaction cytokine, at least in this type of pleural effusion. This seems to be the first study involving the favourable behaviour of IL-6 in the inflammatory reaction of pleura in the acute phase of PCABG surgery.