Characterization of an Antibody That Can Detect the Kai1/CD82 Murine Metastasis Suppressor

Background: Kai1, also known as CD82, is a member of the tetraspanin family (TM4SF). The human homolog, KAI1, is an activation antigen of T-cells and is a metastasis suppressor for prostate and other cancers. Little is known about the mouse protein because of the lack of antibody reagents.

Methods: Peptide immunized rabbits were used to generate polyclonal antibody to Kai1. The antibody was analyzed using immunoblotting, flow cytometry, and immunohistochemistry.

Results: This antibody specifically recognizes murine Kai1 protein, crossreacts with rat Kai1 but not with human KAI1. The normal tissue distribution of this protein in mice is shown to be similar to that of the human homolog. Interestingly, mouse prostatic epithelium showed differential expression within the lobes.

Conclusion: This antibody, the first described that can specifically detect murine Kai1/CD82, should be very useful in addressing the mechanism of action of Kai1 in metastatic suppression.