A collection of 8 rat monoclonal antibodies recognizing the heavy chain (CD11a) of the mouse CD11a/CD18 heterodimer LFA-1. The correponding epitopes organize themselves in 3 spatially distinct structural regions of CD11a :Epitope region A : defined by 6 Monoclonal antibodies (H129-37, H68-98,H35-89, H154-595,H85-326, & H155-141); Epitope region C : defined by the monoclonal antibody H129-296 ; and Epitope region D : defined by the monoclonal antibody H154-163.