title: Antipeptide antibodies define the NH2-terminal structure of the pan-specific hemopoietin interleukin 3.
abstract: Antipeptide antibodies were raised in rabbits against a synthetic peptide including the six NH2-terminal amino acids of the pan-specific hemopoietin interleukin 3 (IL 3). Affinity-purified antibody preparations specific for epitopes determined by residues 1 to 6 were immobilized and used as affinity columns. Up to 98% of IL 3 bioactivity in T cell-conditioned medium was depleted by these columns, as was 71 and 74%, respectively, of IL 3 aberrantly produced by the myeloid leukemias WEHI-274.14 and WEHI-3B. IL 3 produced in vivo in WEHI-3B tumor-bearing mice also bound to the anti-1-6 antibody column, up to 70% of the bioactivity being depleted from ascites fluid and up to 84% from the serum. These results suggest that all IL 3 secreted by T cells and the majority of the IL 3 molecules secreted by myeloid leukemias express epitopes determined by residues 1-6 and cannot have the NH2-terminal amino acid sequence initially reported for IL 3. These six NH2-terminal amino acids share similarities with the NH2-terminal amino acids of several other lymphokines, suggesting an important function for this hexapeptide.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology*; D002846:Chromatography, Affinity; D000939:Epitopes / Q000276:immunology*; D007377:Interleukin-3 / Q000276:immunology* / Q000378:metabolism; D007942:Leukemia, Experimental / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D009363:Neoplasm Proteins / Q000276:immunology*; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology*; D011817:Rabbits; D013601:T-Lymphocytes / Q000378:metabolism
chemical_list: D000906:Antibodies; D000939:Epitopes; D007377:Interleukin-3; D009363:Neoplasm Proteins; D010446:Peptide Fragments