Membrane and soluble forms of Fas (CD95) in peripheral blood lymphocytes and in serum from burns patients

Burn trauma results in disorders of regulation of programmed cell death called apoptosis. Apoptosis of immunocytes is associated with the expression of Fas antigen. There are two major forms of Fas molecule, membranous Fas (mFas) and soluble Fas (sFas). The last form is generated by alternative splicing and differs from mFas by lacking 21 amino acid residues containing the transmembrane domain. We determined the expression of mCD3, mCD4, mCD8 and mFas in peripheral blood lymphocytes and the level of the soluble form of Fas in serum in patients with acute thermal trauma (n=32). As the control blood of healthy volunteers (n=25) was investigated. Compared to healthy volunteers, burn patients showed a remarkable reduction in number of CD3+ lymphocytes in the 24 h following injury, which was accompanied by a decrease in CD4+ but not CD8+ subsets by indirect immunofluorescence method. The decrease of expression of mFas in the patients with acute thermal trauma at all burn disease time was determined simultaneously. We established the decrease of level of sFas during the first (404+/-25 U/ml) and second (352+/-38 U/ml) postburn 10-day periods by the ELISA method. The contents of sFas in serum of healthy volunteers was 534+/-31.8 U/ml. There were no relations between the level of membrane Fas expression and contents of the soluble Fas in serum both in clinical manifestation and survival. We suppose that it is impossible to predict outcomes of burn disease by quantity of CD95+ cells and contents of sFas in serum. However, it is probable that significant deviations from the level of sFas may be attributes of non-revealed accompanying pathology.