Antibodies raised against recombinant or synthetic cpn10 are disclosed. The cpn10 has the sequence GSAGQAFRKFLPLFDRVLVERSAAETVTKGGIMLPEKSQGKVLQATVEAVGSGSKGKGGEIQPVSVKEGDKVLL PEYGGTKVVLDDKDYFLFRDGDILGKYVD. Antibodies are raised against either the entire sequence of cpn10, or a shorter peptide sequence derived from cpn10, such as Ac-AGQAFRKLPI.,AGQAFRKFI.PI., or EKSQGKVLQAT, in which the peptides may have a single amino acid deletion, addition or substitution. The antibodies can be used to terminate pregnancy, suppress tumor cell growth or enhance the immune system.