title: Circulating CD20dim T-lymphocytes increase with age: evidence for a memory cytotoxic phenotype.
abstract: The CD20 antigen has been regarded as a B lineage specific, 35 kDa, non-glycosylated membrane phosphoprotein, which functions as either a Ca2+ ion channel or as a regulatory protein of such a channel. Weak expression of CD20 (CD20dim), however, has recently been reported on a sub-population of T lymphocytes. We present results which confirm the existence of a CD20dim T lymphocyte population and show that such cells have a reduced antibody-binding capacity, when compared to CD20bright B-cells (10337 +/- 642 and 346311 +/- 24264 respectively). In addition, CD20dim cell counts vary with age, with the highest levels occurring in octogenarians: cord blood 0.3 +/- 0.1% (n = 13), 20-60 year-old group 2.1 +/- 1.1% (n = 18) and individuals > or = 61 years of age 6.9 +/- 3.2% (n = 10) (P < 0.001). Further characterization of CD20dim T cells, using three colour flow cytometry, demonstrated a predominantly memory cytotoxic phenotype, in that the cells were CD8+CD28+CD45RO+T-CR alpha beta +CD38-HLA-DR-.
authors.affiliation: Department of Haematology, Northern General Hospital, Sheffield, UK.
authors.forename: I
authors.initials: I
authors.lastname: Storie
authors.forename: G A
authors.initials: GA
authors.lastname: Wilson
authors.forename: V
authors.initials: V
authors.lastname: Granger
authors.forename: D
authors.initials: D
authors.lastname: Barnett
authors.forename: J T
authors.initials: JT
authors.lastname: Reilly
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000937:Antigen-Antibody Reactions; D018951:Antigens, CD20 / Q000097:blood*; D005312:Fetal Blood / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D007156:Immunologic Memory; D016130:Immunophenotyping; D007231:Infant, Newborn; D008875:Middle Aged; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic
chemical_list: D018951:Antigens, CD20