CD26 surface antigen expression on peripheral blood T lymphocytes from children with Down's syndrome (trisomy 21).
A phenotypical analysis carried out by two-colour flow cytometry showed that the proportion of circulating CD4+ T lymphocytes co-expressing the membrane-associated ectoenzyme dipeptidyl peptidase IV (CD26 antigen), a functional collagen receptor involved in T-cell triggering through its interaction with the CD45 protein tyrosine phosphatase, was significantly lower in 28 children with non-translocated trisomy 21 (Down's syndrome) (DS) than that calculated in the bloodstream of 27 age- and sex-matched healthy controls. Agonist anti-CD26 monoclonal antibodies (MoAbs), such as anti-1F7, not only modulate the surface expression of this molecule, but also enhance the proliferative activity of normal human T cells via the CD3- and CD2-mediated activation pathways. T-lymphocyte proliferation induced by antigen or polyclonal T-cell activators, including anti-CD3 or -CD2 MoAbs, is severely impaired in DS. Although the physiological ligand of CD26 surface structure is unknown, the fact that CD4+ T lymphocytes found in the blood of trisomic subjects are mostly CD26- (anti-1F7-) suggests that their faulty mitogenic response may be due to phenotypical and, perhaps, strictly correlated functional abnormalities.
Bertotto
A
A
Department of Paediatrics, Perugia University Medical School, Italy.
Gerli
R
R
Spinozzi
F
F
Muscat
C
C
Fabietti
G M
GM
Crupi
S
S
Castellucci
G
G
De Benedictis
F M
FM
De Giorgi
G
G
Britta
R
R
D000293:Adolescent; D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis* / Q000097:blood / Q000276:immunology; D018801:CD2 Antigens; D017252:CD3 Complex / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D018819:Dipeptidyl Peptidase 4; D004314:Down Syndrome / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D016130:Immunophenotyping; D007223:Infant; D008297:Male; D011971:Receptors, Immunologic / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D017252:CD3 Complex; D011971:Receptors, Immunologic; D018819:Dipeptidyl Peptidase 4