Generation of anti-peptide monoclonal antibodies which recognize mature CSF-2 alpha (IL 3) protein.

The colony-stimulating factor CSF-2 alpha (IL 3) has been purified to homogeneity, the protein sequenced, and the gene encoding this lymphokine cloned. Knowledge of the protein sequence permitted the synthesis of peptides corresponding to the amino terminus of the molecule. These peptides, after conjugation to palmitic acid, were used to immunize mice. Spleen cells from mice immunized with one of these peptides (CSF-2 alpha 1-14) were fused with the myeloma cell line NS-1. The fusion resulted in the isolation of two hybridoma cell lines, designated 6A5 and 4D4, that secreted antibodies that were specific for the immunizing peptide. The antibodies did not react with a closely related peptide CSF-2 alpha 7-16. The antibodies were capable, however, of recognized CSF-2 alpha protein as judged by the ability of the antibodies to remove CSF-2 alpha activity from culture medium of PHA-stimulated LBRM-33-5A4 cells, to immunoprecipitate radiolabeled CSF-2 alpha protein, and to detect CSF-2 alpha protein bound to nitrocellulose membranes.