The monoclonal antibody Mac 387 recognizes three S100 proteins in human neutrophils

Mac 387, a murine mAb, was previously described to detect a complex form of MRP-14 and MRP-8, two calcium-binding proteins of the S100 family, but recent experiments suggested that Mac 387 recognized only MRP-14. Using two-dimensional polyacrylamide gel electrophoresis and the very sensitive enhanced chemiluminescence detection system, the immunoreactivity of Mac 387 was compared with that of a polyclonal antibody raised against purified MRP-8, but cross-reacting with MRP-14 and p6, a novel S100 protein. Under such conditions, Mac 387 was found to recognize the three S100 proteins. This result suggests that Mac 387 might recognize an epitope common to the proteins of the S100 family.