The CD 155 ligand CD96 is an immunoglobulin-like protein tentatively allocated to the repertoire of human NK receptors. We report here that the CD96/CD 155-interaction is preserved between man and mouse although both receptors are only moderately conserved in amino acid sequence. Moreover, murine CD96 (mCD96) binds to nectin-1, a receptor related to CD155. Applying newly generated monoclonal antibodies specifically recognizing mCD96, an expression profile is revealed resembling closely that of human CD96 (hCD96) on cells of hematopoietic origin. A panel of anti-mCD96 but also recently established anti-mCD155 antibodies effectively prevents formation of CD96/CD 155-complexes. This was exploited to demonstrate that the only available receptor for mCD96 present on thymocytes is mCD155. Moreover, T cell adhesion to insect cells expressing mCD 155 is blocked by these antibodies depending on the T cell subtype. These results suggest a function of the CD96/CD155-adhesion system in T cell biology. (C) 2007 Elsevier Inc. All rights reserved.