Numerous cell adhesion molecules found on leukocytes, endothelial cells, and platelets are involved in a central way in many biological functions and disease processes. These cell adhesion molecules include members of the immunoglobulin gene superfamily, integrins, selectins, and other proteins. This project focuses particularly on the beta-2 subunit of leukocyte integrins (CD18), intercellular adhesion molecule-1 (ICAM-1), and granule membrane protein-140 (GMP-140). The overall goals of this project are to generate mutations in the CD18, ICAM-1, and GMP-140 genes in the mouse using homologous recombination in embryonic stem (ES) cells. These mouse mutants would be used to study the role of these proteins in normal biological function and in disease. There is substantial evidence that these proteins play central roles in processes such as inflammation, autoimmune disease, infectious susceptibility, transplantation rejection, and perhaps atherosclerosis. The murine genes would be cloned and characterized in sufficient detail to prepare constructs for homologous recombination in ES cells. The CD18, ICAM-1, and GMP-140 genes would be interrupted by homologous recombination in ES cells using insertion and/or replacement vectors, tissue culture selection, screening with the polymerase chain reaction (PCR), and confirmation of homologous recombination with Southern blotting. Mutant ES cells would be introduced into mouse blastocysts to obtain chimeras and subsequently bred into the mouse germ-line. The phenotype of heterozygous and homozygous mutant mice will be examined clinically, pathologically, and physiologically. The effect of mutant phenotypes on murine autoimmune processes will be studied using model systems such as experimental allergic encephalomyelitis, lupus erythematosus, and diabetes mellitus. The effects of the mutant phenotypes on murine atherosclerosis will be examined using mice with putative atherosclerosis genotypes. Mutant mice will be made available on a collaborative basis and rapidly on an unlimited basis to other laboratories in order to facilitate analysis of other biological features of any mutant animals. There will be a sharp focus on obtaining null mutations in CD18, ICAM-1, and GMP-140 and on introducing these into the mouse germ-line in the first 1-3 years of the project.