BOVINE MELANOMA GROWTH-STIMULATORY ACTIVITY - A NEW MONOCYTE-MACROPHAGE DERIVED CYTOKINE OF THE IL-8 FAMILY - PARTIAL STRUCTURE, FUNCTION, AND EXPRESSION IN ACUTE PULMONARY INFLAMMATION

BACKGROUND: Neutrophil-chemotactic peptides are a family of small basi c peptides 70 to 80 amino acids in length. They contain four conserved cysteine residues, the first two spaced by one amino acid (C-X-C). Th e best characterized species is human IL-8. Other prominent members ar e melanoma growth stimulatory activity (GRO-alpha), neutrophil-activat ing peptide-2, and epithelial-cell derived neutrophil-activating prote in 78. EXPERIMENTAL DESIGN: Bovine monocytes and alveolar macrophages were induced by lipopolysaccaride, and a major neutrophil chemotactic activity in the supernatant was purified by cation-exchange chromatogr aphy and reversed-phase HPLC, The chemotaxin was then analyzed for bio logic activity on bovine neutrophils by in vitro chemotaxis, shape cha nge, and transient rise of intracellular-free calcium concentration. T he in vivo role of bovine GRO (boGRO) was tested immunohistologically in confirmed cases of pneumonic pasteurellosis. RESULTS: We have purif ied and partially sequenced a bovine homologue of human GRO-alpha. The partial amino acid sequence of boGRO was: APVVNELRCQCLQTLQIHLKNIQSVKV TTPGP. BoGRO was biologically active and induced a dose-dependent neut rophil migration in the range of 10(-7) to 10(-9) M. BoGRO also induce d a dose-dependent shape change in bovine neutrophils similar to human IL-8. This effect was detectable down to 10(-10) M. Similar effects w ere observed on the transient rise of intracellular-free calcium conce ntration. In bovine pneumonic pasteurellosis and, to a lesser extent, in normal lungs, immunoreactivity to human GRO was highly positive in hypertrophic type-II epithelial cells and in mesothelial cells, wherea s pleural fibroblasts and bronchial epithelial cells were negative. CO NCLUSIONS: BoGRO is a prominent neutrophil chemoattractant secreted by monocytes and alveolar macrophages. It is active at similar concentra tions as human IL-8. The strong immunoreactivity in type-II epithelial and mesothelial cells of bovine pneumonia strongly suggest a role for boGRO in the genesis of pulmonary inflammation.