title: Phenotypical and functional characterization of double-negative (CD4-CD8-) alpha beta T-cell receptor positive cells from an immunodeficient patient.
abstract: We have characterized CD4-CD8- double-negative (DN) alpha beta TCR+ T cells from a patient with immunodeficiency, lymphocytosis, lymphadenopathy, and hepatosplenomegaly. The majority of peripheral blood lymphocytes were DN alpha beta TCR+ T cells as evaluated by FACS and biochemical analysis. The DN T cells showed the following phenotype: alpha beta TCR+, gamma delta TCR-, CD2+, CD3+, CD4-, CD5+, CD7-, CD8-, CD16-, CD25-, CD26-, CD28+, CD45RO-, CD45RA+, CD57+, and HLA-DR+. Both southern blot analysis of TCR genes and FACS analysis applying a panel of V beta and V alpha monoclonal antibodies (MoAbs) indicated a polyclonal T-cell expansion. Thymic biopsy showed normal histology, whereas lymph node biopsy samples showed altered histological and immunohistological patterns with markedly expanded paracortical areas containing the DN T cells of the same phenotype as found in peripheral blood T cells. In functional studies, the DN T cells showed a profoundly reduced proliferative response upon stimulation with mitogens as well as MoAbs against the TCR/CD3 complex, CD2, and CD28, respectively. Addition of exogenous interleukin-2 (IL-2) only minimally augmented the proliferative response. In contrast, the addition of a combination of Ca2+ ionophore and phorbol 12-myristate 13-acetate (PMA) restored the proliferative response of the DN T cells to almost normal levels. This observation strongly suggests that the protein kinase C activity of the DN T cells was intact, but that the normal mechanism for transmembrane signal transduction was impaired in these unusual DN T cells.
authors.affiliation: Department of Paediatrics, University of Copenhagen, Denmark.
authors.forename: N
authors.initials: N
authors.lastname: Illum
authors.forename: E
authors.initials: E
authors.lastname: Ralfkiaer
authors.forename: G
authors.initials: G
authors.lastname: Pallesen
authors.forename: C
authors.initials: C
authors.lastname: Geisler
mesh_terms: D015703:Antigens, CD / Q000032:analysis; D015704:CD4 Antigens / Q000032:analysis*; D016827:CD8 Antigens / Q000032:analysis*; D002648:Child; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000276:immunology* / Q000473:pathology; D008198:Lymph Nodes / Q000473:pathology; D008213:Lymphocyte Activation; D010641:Phenotype; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis*; D013601:T-Lymphocytes / Q000276:immunology* / Q000502:physiology; D013950:Thymus Gland / Q000473:pathology
chemical_list: D015703:Antigens, CD; D015704:CD4 Antigens; D016827:CD8 Antigens; D016693:Receptors, Antigen, T-Cell, alpha-beta