Abstract: Polypeptides comprising amino acid sequences of particulate antigens isolated from various species of Leishmania protozoa, or immunogenic variants thereof, are disclosed for the treatment and clinical remission of psoriasis. Also disclosed are nucleic acid sequences encoding such polypeptides, vectors incorporating such nucleic acid sequences, methods for genetically engineering microbial host cells to produce such polypeptides, and such recombinant microbial host cells. In another embodiment, immunotherapeutic agents incorporating the polypeptides or the nucleic acid sequences are disclosed for the treatment and clinical remission of psoriasis. In another embodiment, methods for the production of the polypeptides using recombinant microbial host cells are disclosed. Finally, methods for the treatment and clinical remission of psoriasis comprising administration of a pharmaceutical composition comprising one or more of the polypeptides or one or more of the nucleic acid sequences are disclosed.