Effect of partially modified retro-inverso analogues derived from C-reactive protein on the induction of nitric oxide synthesis in peritoneal macrophages

The ability of three modified tetrapeptides, representing fragments of the C-reactive protein (CRP) sequence and stabilized in the first peptide bond by retro-inverso modification, to affect the secretion of nitric oxide (NO) was studied in macrophages of BALB/c mice. These tetrapeptides, resembling the aminoacid sequence of tuftsin (CRP I, H-gThr-(R,S)mLys-Pro-Leu-OH, ITF 1192; CRP II, H-gGly-(R, S)mLys-Pro-Arg-OH, ITF 1127; CRP III, H-gThr-(R,S)mLys-Pro-Gln-OH, ITF 1193), were able to induce NO synthesis by peritoneal macrophages in a dose-dependent manner; the most stimulating dose was 1000 ng ml−1 for CRP II and 100 ng ml−1 for CRP I and CRP III. NO synthesis was not strictly dependent …