B-cell epitope peptides of HSP 65, particularly the peptides comprising the amino acid sequence substantially as denoted by SEQ ID: Nos. 1-5 and their biologically functional homologues and derivatives thereof. Also included are polyclonal and monoclonal antibodies directed against them and their compositions for passive immunization against inflammatory and autoimmune diseases and in the treatment of inflammatory and autoimmune diseases. Also encompassed are diagnostic uses of these antibodies, for identifying people at risk of developing arthritis or diabetes, and a method of monitoring progress of the disease conditions and disease prognosis.