Induction of CD69 antigen on normal CD4+ and CD8+ lymphocyte subsets and its relationship with the phenotype of responding T-cells.
We evaluated phenotype and apoptotic status of normal CD4+CD69+ and CD8+CD69+ peripheral blood T-lymphocytes after short-term challenge with escalating concentrations of phytohemagglutinin (PHA). The frequency of CD69-coexpressing CD4+ and CD8+ T-cells and CD69 staining intensity increased following T-cell mitogenic stimulation; these changes were proportional to PHA concentration in culture medium. A considerable fraction of lymphocytes underwent blast transformation, displaying increased forward and side scatter signals. Interestingly enough, PHA-responsive T-cells exhibited a predominantly CD25negCD38negTCRalphabetapos phenotype; APO-1/Fas antigen (CD95) could be detected on a minority of activated CD69+ T-cells. A considerable proportion of CD69+ lymphocytes expressed intracellular perforin; in addition, an average 16+/-6% CD69+ T-lymphocytes were apoptotic after 4 h of stimulation, as evaluated by 7-amino-actinomycin-D staining and by annexin-V binding. CD69+ activated lymphocytes comprise phenotypically heterogeneous cell subpopulations potentially devoted to diverse immunological functions, i.e., proliferation, apoptosis, or cell cytotoxicity; moreover, our findings indicate that CD69 expression is proportional to the intensity of the activating stimulus and that the capacity to upregulate CD69 antigen following short-term mitogenic challenge may be restricted to unactivated CD38negCD25negTCRalphabetapos T-lymphocytes.
Department of Hematology, Catholic University, Rome, Italy. srutell@tin.it
S
S
Rutella
C
C
Rumi
M B
MB
Lucia
T
T
Barberi
P L
PL
Puggioni
M
M
Lai
A
A
Romano
R
R
Cauda
G
G
Leone
D017304:Annexin A5 / Q000378:metabolism; D015703:Antigens, CD / Q000096:biosynthesis*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis*; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D006801:Humans; D016130:Immunophenotyping; D037181:Lectins, C-Type; D008934:Mitogens / Q000494:pharmacology; D010835:Phytohemagglutinins / Q000494:pharmacology; D000099192:CD69 Antigens
D017304:Annexin A5; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D037181:Lectins, C-Type; D008934:Mitogens; D010835:Phytohemagglutinins; D000099192:CD69 Antigens