title: Activation of CD3/TCR negative human thymocytes via CD28 molecule.
abstract: We have observed that the CD28 molecule was present on the cell surface of a large fraction of resting CD3- thymocytes (40 to 100%). Interestingly, the majority (greater than 90%) of surface CD3-CD28-cells reacted in the cytoplasm with anti-CD28 (CK248, 9.3) and anti-CD3 epsilon chain mAbs (Leu4, OKT3). Along this line, we found that CD28 surface expression could be induced within 18 hr on CD3-CD28- thymocytes using very low doses of phorbol-13-myristate-12-acetate (PMA). This event was accompanied by the appearance of CD25 and CD69 activation antigens but not of CD3/TCR complex. These results were further confirmed by immunoprecipitation studies. It is noteworthy that the T-cell activation pathway initiated via the CD28 molecule is functional in resting CD3- thymocytes in the presence of PMA and/or IL2. Finally, stimulation of CD3- immature thymocytes via CD28 gave rise to a large fraction (about one-third) of CD3-CD8+ cells.
authors.affiliation: Istituto Scientifico San Raffaele, Milan, Italy.
authors.forename: M R
authors.initials: MR
authors.lastname: Zocchi
authors.forename: A
authors.initials: A
authors.lastname: Poggi
mesh_terms: D015703:Antigens, CD / Q000502:physiology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis* / Q000502:physiology*; D018106:CD28 Antigens; D017252:CD3 Complex; D002675:Child, Preschool; D003593:Cytoplasm / Q000276:immunology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D011948:Receptors, Antigen, T-Cell / Q000032:analysis*; D015375:Receptors, Interleukin-2 / Q000032:analysis; D013601:T-Lymphocytes / Q000276:immunology*; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D018106:CD28 Antigens; D017252:CD3 Complex; D037181:Lectins, C-Type; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2; D000099192:CD69 Antigens