NK-lysin, a novel effector peptide of cytotoxic T and NK cells. Structure and cDNA cloning of the porcine form, induction by interleukin 2, antibacterial and antitumour activity.

Abstract

A 78 residue antimicrobial, basic peptide, NK‐lysin, with three intrachain disulfide bonds was purified from pig small intestine and characterized. A corresponding clone was isolated from a porcine bone marrow cDNA library. The 780 bp DNA sequence had a reading frame of 129 amino acids which corresponded to NK‐lysin. The clone was used to show that stimulation with human interleukin‐2 induced synthesis of NK‐lysin‐specific mRNA in a lymphocyte fraction enriched for T and NK cells. Lower levels of mRNA were detected in tissues known to contain T and NK cells, such as small intestine, spleen and colon. Interleukin‐2 also induced both proliferation of the lymphocyte fraction and cytolytic function in these cells. Immunostaining showed that NK‐lysin was present in cells positive for CD8, CD2 and CD4. NK‐lysin showed high anti‐bacterial activity against Escherichia coli and Bacillus megaterium and moderate activity against Acinetobacter calcoaceticus and Streptococcus pyogenes. The peptide showed a marked lytic activity against an NK‐sensitive mouse tumour cell line, YAC‐1, but it did not lyse red blood cells. The amino acid sequence of NK‐lysin exhibits 33% identity with a putative human preproprotein, NKG5, of unknown function but derived from a cDNA clone of activated NK cells. We suggest that NK‐lysin is a new effector molecule of cytotoxic T and NK cells.

NK-lysin of channel catfish: Gene triplication, sequence variation, and expression analysis

“…The NK-lysin gene was initially cloned and characterized from humans, but its significance was unrealized until its orthologue was identified from porcine natural killer cells and cytotoxic T lymphocytes as an antimicrobial peptide (Manning et al, 1992;Houchins et al, 1993;Andersson et al, 1995). In recent years, extensive research has been conducted for the analysis of structure and antimicrobial activities of NK-lysin (Stenger et al, 1998;Ernst et al, 2000;Gansert et al, 2003;Jacobs et al, 2003).…”

“…Recently, with the discovery of porcine NK-lysin and human granulysin (Andersson et al, 1995;Pena et al, 1997), a fifth class of antimicrobial polypeptides has been recognized in natural killer and T cells . Compared with the classical antimicrobial peptides, NK-lysin and granulysin are much larger with 78 and 74 amino acid residues and a globular three-dimensional structure.…”

Role of intestinal epithelial cells in the innate immune defence of the pig intestine

“…NK-lysin is another antimicrobial peptide purified from the porcine small intestine based on its antibacterial activity and that has been shown to be a new effector molecule of cytotoxic T and NK cells [3,66]. This antimicrobial peptide shows activity against various bacteria and fungi, including Escherichia coli, Bacillus megaterium, Acinetobacter calcoaceticus, Streptococcus pyogeneis, and Candida albicans [3].…”

“…This antimicrobial peptide shows activity against various bacteria and fungi, including Escherichia coli, Bacillus megaterium, Acinetobacter calcoaceticus, Streptococcus pyogeneis, and Candida albicans [3]. It lyses certain tumour cells, but not erythrocytes.…”

“…It lyses certain tumour cells, but not erythrocytes. Antimicrobial and tumourolytic activities of NK-lysin are believed to arise from its interaction with lipids and ability to form pores in the cell membrane because of its alpha-helical structure [3].…”