Circulating CD20dim T-lymphocytes increase with age: evidence for a memory cytotoxic phenotype.
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-.
Storie
I
I
Department of Haematology, Northern General Hospital, Sheffield, UK.
Wilson
G A
GA
Granger
V
V
Barnett
D
D
Reilly
J T
JT
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
D018951:Antigens, CD20