The invention concerns the use of a protein derived from cancel cells, cells infected by a virus or immune cells or an inactive fragment of said protein, said protein being initially an immunosuppressive and/or an angiogenic protein with local activity whereof said properties have been inactivated by at least 70% by a physical and/or chemical treatment, such as formolisation, carboxamidation, carboxymethylation, maleimidation or oxidation by oxygen bubbling, by genetic recombination or by adjuvant conditioning, said treatment preserving its property of being identified by antibodies directed against said protein, and preserving sufficient immunogenic properties for generating antibodies neutralizing or blocking said native protein, or the use of a DNA molecule corresponding to said protein inactivated by mutation or to said inactive fragment, for obtaining a medicine designed to provide a patient with mucosal immunity based on secretion of IgA secretory antibodies, pharmaceutical compositions for the mucous membranes and IgA antibodies.