A composition and method for stimulating an immune response against an antigen in immunised individuals or in cell groups. The composition comprises a protein called Lip2a Leishmania formed by a sequence of amino acids coded for by a sequence of DNA that comprises the nucleotides: 1-1 of nos. 778 to 1231 of SEQ. ID NO ! 1-2 or formed by a sequence of nucleotides able to hybridise with the sequence described in 1-1 under moderately strict hybridisation conditions and which would therefore code for a protein similar to Lip2a. The method comprises incubating said cells with said Lip2a protein in the presence or not of an antigen specific to a disease or infection.
