title: CD11b (Mac-1): a marker for CD8+ cytotoxic T cell activation and memory in virus infection.
abstract: We have found that CD11b, a cell surface integrin of macrophages, granulocytes, and NK cells, is expressed by a subset of CD8+ T cells that include both the active virus-specific CTL and the virus-specific memory CTL populations. CD8+CD11b+ cells comprise less than 3% of naive mouse splenocytes, but after lymphocytic choriomeningitis virus (LCMV) infection increase by 9- to 12-fold by the peak (day 8) of the virus-specific CTL response. Depletion of day-8 splenocytes with anti-Mac-1 and C' or enrichment by sorting for CD11b+ or CD8+CD11b+ spleen cells demonstrated that LCMV-specific CTL are CD11b+. The CD11b+ subpopulation also contained the bulk of the IL-2-responsive CD8+ cells. MEL-14, a homing marker down-regulated on activated T cells, was down-regulated on the majority of CD8+ cells that became CD11b+. Less than 1% of LCMV-immune splenic lymphocytes expressed CD11b. Antibody and C' depletion of this population severely impaired the ability of immune splenocytes to respond to in vitro secondary stimulation with LCMV-infected peritoneal macrophages, but did not affect the generation of a primary allospecific CTL response in MLC. Mixing of CD8-depleted and CD11b-depleted LCMV-immune splenocytes failed to restore the ability of these cells to mount a virus-specific memory CTL response, indicating that a cell coexpressing CD8 and CD11b is essential for this response. As determined by limiting dilution analysis, the precursors for the LCMV-specific memory CTL response were enriched in the CD11b+ population of LCMV-immune splenocytes. CD11b stained far fewer CD8+ splenocytes from naive mice than did CD44 (Pgp-1), and among immune splenocytes it identified a small subpopulation of CD44hi cells, indicating that CD11b may be the best single marker available for discriminating between naive and memory CD8+ T cells.
authors.affiliation: Department of Pathology, University of Massachusetts Medical Center, Worcester 01655.
authors.forename: H I
authors.initials: HI
authors.lastname: McFarland
authors.forename: S R
authors.initials: SR
authors.lastname: Nahill
authors.forename: J W
authors.initials: JW
authors.lastname: Maciaszek
authors.forename: R M
authors.initials: RM
authors.lastname: Welsh
mesh_terms: D000818:Animals; D016827:CD8 Antigens / Q000032:analysis; D002469:Cell Separation; D005434:Flow Cytometry; D007111:Immunity, Cellular; D007156:Immunologic Memory; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation; D008216:Lymphocytic Choriomeningitis / Q000276:immunology*; D016177:Macrophage-1 Antigen / Q000276:immunology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D016201:Receptors, Lymphocyte Homing / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D016827:CD8 Antigens; D007376:Interleukin-2; D016177:Macrophage-1 Antigen; D016201:Receptors, Lymphocyte Homing