Digital Database for Screening Mammography (DDSM) is an invaluable resource that has been widely used for digital mammography research. The primary purpose of the database is to facilitate research in the development of computer algorithms to aid in screening mammography and the development of teaching or training aids. In the last decade, several techniques of artificial intelligence proved their skills in the field of classification of cancer cells. In this aim, and to improve the classification of DDSM database, we propose in this article an improvement of CLONALG algorithm, which is based on Artificial Immune System (AIS) principle.