title: Effects of human immunodeficiency virus type 1 on CD4 lymphocyte subset activation.
abstract: The pathogenesis of the decline of CD4 lymphocyte counts accompanying the typical course of HIV-1 infection is not completely defined and might be related to a differential susceptibility of naive and memory cells to HIV-1 exposure. Here, we examined the effects induced by heat-inactivated HIV-1 virions on these lymphocyte populations. Exposure of CD45RA naive T cells to inactivated viral particles induced a marked decrease of both mitogenic responses and activation-induced apoptosis. Conversely, the growth of CD45RO cells was less severely restrained. Analysis of intracellular levels of cell cycle regulatory proteins revealed an arrest at the G1/S restriction point of the naive but not memory subset. This effect was associated with alterations in phosphotyrosine profile and with a marked decrease of ERK and NJK kinase activation. Finally, up-regulation of the cAMP-dependent protein kinase A (PKA) activity induced by mitogens was not affected by virus. Altogether, these findings show that interaction of HIV-1 with the T cell surface is sufficient to inhibit the proliferative response of the CD4CD45RA subset by disturbing proximal TCR signaling. This mechanism would affect renewal of naive lymphocytes, contributing in such a way to the impairment of T cell turnover during the course of HIV-1 infection.
authors.affiliation: Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, Naples, Italy.
authors.forename: A M
authors.initials: AM
authors.lastname: Masci
authors.forename: F L
authors.initials: FL
authors.lastname: Paz
authors.forename: A
authors.initials: A
authors.lastname: Borriello
authors.forename: S
authors.initials: S
authors.lastname: Cassano
authors.forename: V
authors.initials: V
authors.lastname: Della Pietra
authors.forename: H
authors.initials: H
authors.lastname: Stoiber
authors.forename: G
authors.initials: G
authors.lastname: Matarese
authors.forename: F
authors.initials: F
authors.lastname: Della Ragione
authors.forename: S
authors.initials: S
authors.lastname: Zappacosta
authors.forename: L
authors.initials: L
authors.lastname: Racioppi
mesh_terms: D017209:Apoptosis / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D042846:CDC2-CDC28 Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002453:Cell Cycle; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D056743:Cyclin D3; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004789:Enzyme Activation; D015658:HIV Infections / Q000276:immunology / Q000473:pathology; D015497:HIV-1 / Q000276:immunology* / Q000472:pathogenicity*; D006358:Hot Temperature; D006801:Humans; D007156:Immunologic Memory; D066298:In Vitro Techniques; D017493:Leukocyte Common Antigens / Q000378:metabolism; D008213:Lymphocyte Activation; D019000:Phosphotyrosine / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D015398:Signal Transduction / Q000276:immunology
chemical_list: C534696:CCND3 protein, human; D056743:Cyclin D3; D016213:Cyclins; D019000:Phosphotyrosine; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D017493:Leukocyte Common Antigens; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1