Spleen antibacterial peptides: high levels of PR-39 and presence of two forms of NK-lysin

Antibacterial peptides were isolated from porcine spleen by acetic acid ext raction, ion exchange chromatography and reverse-phase high-performance liq uid chromatography. C-terminal ladder sequence analysis of a bioactive pept ide with matrix-assisted laser desorption:ionization mass spectrometry afte r digestion with carboxypeptidases P and Y showed that it is identical to t he antibacterial proline/arginine-rich intestinal peptide PR-39. it is pres ent at high levels in granulocytes of the spleen, and peptides with C-termi nal proline amide and internal adjacent Pro residues can be analyzed with t his method. In addition, two forms of NK-lysin (NKL were found. One, NKLi, is identical to that isolated from pig intestine, and the other, NKLbw, to a mature peptide deduced from a clone from a porcine bone marrow cDNA libra ry.