CD4dullCD8bright double-positive T-lymphocytes have a phenotype of granzyme Bpos CD8pos memory T-lymphocytes.
BACKGROUND
T-lymphocytes that co-express CD4 and CD8 antigens may be found in small percentages in the peripheral blood of healthy individuals, and have a CD4brightCD8dull phenotype. CD4dullCD8bright T-lymphocytes have been found only in temporal association with some viral infections.


METHODS
Four-colour flow cytometric analysis of peripheral blood mononuclear cells from a renal transplant recipient with cytomegalovirus infection was performed.


RESULTS
A small but clearly distinguishable subpopulation of CD4dullCD8bright double-positive T-lymphocytes was detected, that exhibited phenotypic characteristics of cytotoxic T-lymphocytes and were granzyme B positive. Furthermore, no naive cells appeared to be present within this subpopulation.


CONCLUSIONS
CD4dullCD8bright double-positive T-lymphocytes are enriched for memory and effector cytotoxic T cells.
Rentenaar
R J
RJ
Department of Internal Medicine, Academic Medical Centre, University of Amsterdam, The Netherlands.
Wever
P C
PC
van Diepen
F N
FN
Schellekens
P T
PT
Wertheim
P M
PM
ten Berge
I J
IJ
D015704:CD4 Antigens / Q000032:analysis*; D016827:CD8 Antigens / Q000032:analysis*; D005260:Female; D053804:Granzymes; D006801:Humans; D007156:Immunologic Memory; D016130:Immunophenotyping; D008875:Middle Aged; D012697:Serine Endopeptidases / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology*
D015704:CD4 Antigens; D016827:CD8 Antigens; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases