title: CD4+ CD8+ cells are rare among in vitro activated mouse or human T lymphocytes.
abstract: The predominant cell type in the thymus expresses both of the function-associated T cell surface markers, CD4 and CD8, but CD4+ CD8+ cells are rare or absent outside the thymus. Double expression has therefore been assumed to be an indication of immaturity. However, recent reports have suggested that CD4+ CD8+ cells can appear in cultures of activated mature cells. We have therefore activated human peripheral blood lymphocytes and mouse spleen cells, lymph node cells, and cortisone-resistant thymocytes using a number of different stimulation regimes, and we have analyzed them at various times for CD4 and CD8 expression. In all cases, upon analysis of cultured cells by flow cytometry, CD4+ CD8+ cells were rare. A combination of microscopic analysis, cell sorting followed by microscopic analysis, and careful staining controls demonstrated that even when flow cytometry showed some CD4+ CD8+ cells, most of these were artifacts in the form of doublets or clumps of single positive cells or dead cells. Taking this into account, CD4+ CD8+ cells made up less than 1% in the mouse and less than 3% in the human T cell cultures at any time periods. We therefore found no evidence for the generation of large numbers of CD4+ CD8+ cells in cultures of mouse or human T cells.
authors.affiliation: Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.
authors.forename: K
authors.initials: K
authors.lastname: Kelly
authors.forename: L
authors.initials: L
authors.lastname: Pilarski
authors.forename: K
authors.initials: K
authors.lastname: Shortman
authors.forename: R
authors.initials: R
authors.lastname: Scollay
mesh_terms: D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D002469:Cell Separation; D002478:Cells, Cultured; D005434:Flow Cytometry; D006801:Humans; D007958:Leukocyte Count; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D010641:Phenotype; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte