[A peptide (a magnesium salt of N-acetyl (alpha, beta)-aspartyl-glutamic acid). Demonstration of the protection against local cellular destruction induced by in situ complement activation].

A peptide of simple chemical structure has demonstrated its efficiency in preventing the large cellular destruction that locally activated complement produced on the ciliary epithelium of the respiratory tract. Previously (1980), it was demonstrated by the authors that these cellular destructions after sensitization of the epithelium was due to the local activation of the complement (alternate pathway) by immune complexes with secretory IgA. The cellular protection afforded by Naaga was demonstrated by the persistance of a normal ciliary beating when the sensitized mucosa is in contact with the antigen; by electron microscopic studies both in transmission and scanning E.M. contrasting with the complete cellular destructions of the epithelium which appear obvious. The protection appear complete when Naaga (56 mM) is present in the testing solution (or instillated before the test). By in vitro human complement studies; study of the cytolytic sequence inhibition for the classical pathway 1,5.10(-3) M of Naaga produces a 50% inhibition of 1 H50 hemolytic unit. For the alternate pathway, the same inhibition is observed with 1,75.10(-3) M of Naaga; by two-dimensions immuno-electrophoresis: a dilution of 1/2 of C3 in Naaga reduced to 1/10 of its normal value the C3b profile; the "Rockets" technique demonstrated that the same 1/2 dilution of Naaga in complement prevents the clivage of factor B and that this peptide acts by inhibition of the alternate C3 convertase formation (see illustrations). If we consider the subject of this study i.e. the upper respiratory tract mucosa and knowing the physiopathological importance of the muco ciliary complex in preventing dust, microbs and other particulate foreign materiel to penetrate the epithelium, the therapeutic importance of such a simple non toxic and unharmful chemical compound must be stressed.