RESUMEN
The thymus is the major site for T cell development; interactions of developing thymocytes with thymic epithelial cells are critical for normal thymopoiesis. We set out to determine whether thymic epithelial cells can be infected by HIV strains that cause different patterns of disease progression in infected infants. Thymic epithelial cell monolayers were prepared from normal thymus of infants, removed at the time of cardiac surgery. We infected the thymic epithelial cell monolayers with different strains of HIV, including laboratory strains and clinical strains from 3 of our pediatric HIV-infected patients with different patterns of disease progression. We found that different strains of HIV have different ability to infect thymic epithelial cells; the ability to infect thymic epithelial cells may not be directly related to CCR5/CXCR4 usage. Different HIV strains thus appear to employ different mechanisms by which they affect thymic components.
Asunto(s)
Células Epiteliales/virología , VIH-1/crecimiento & desarrollo , Timo/virología , Células Cultivadas , Preescolar , ADN Viral/análisis , Células Epiteliales/citología , VIH-1/genética , VIH-1/patogenicidad , Humanos , Lactante , Reacción en Cadena de la Polimerasa , Timo/citología , Replicación ViralRESUMEN
The authors evaluated the lymphocyte subsets in eight children with the DiGeorge anomaly, compared with 48 age-matched control infants. Of particular interest was the finding that the percentage and number of CD5+ B lymphocytes were decreased in seven of the eight cases. This observation may provide insight into thymic function and the interaction of the B and T cell systems in some forms of congenital and acquired immunodeficiencies.
Asunto(s)
Linfocitos B/inmunología , Antígenos CD5/inmunología , Síndrome de DiGeorge/inmunología , Antígenos CD19/inmunología , Preescolar , Citometría de Flujo , Humanos , Lactante , Recién Nacido , Recuento de Linfocitos , Subgrupos LinfocitariosAsunto(s)
Complejo Mycobacterium avium/inmunología , Infección por Mycobacterium avium-intracellulare/inmunología , Osteomielitis/inmunología , Adolescente , Femenino , Humanos , Complejo Mycobacterium avium/aislamiento & purificación , Infección por Mycobacterium avium-intracellulare/microbiología , Infección por Mycobacterium avium-intracellulare/patología , Infección por Mycobacterium avium-intracellulare/fisiopatología , Osteomielitis/microbiología , Osteomielitis/patología , Osteomielitis/fisiopatología , RecurrenciaAsunto(s)
Antígenos CD/análisis , Subgrupos de Linfocitos B/inmunología , Sangre Fetal/inmunología , Infecciones por VIH/inmunología , Recién Nacido/inmunología , Adolescente , Adulto , Envejecimiento/inmunología , Formación de Anticuerpos , Antígenos CD5 , Niño , Preescolar , Ensayo de Inmunoadsorción Enzimática , Femenino , Técnica del Anticuerpo Fluorescente , Anticuerpos Anti-VIH/análisis , Infecciones por VIH/embriología , Seropositividad para VIH , Humanos , Lactante , Embarazo , Valores de ReferenciaRESUMEN
We tested human immunodeficiency virus type 1 (HIV-1) antibody-positive human sera and sCD4, alone and in combination, for synergistic, additive, or antagonistic effects on blocking of HIV binding and infectivity. Data were analyzed by an application of the median effect principle derived from the law of mass action. This allows the assessment of synergism/antagonism at any desired level of effect. Using three assays (whole virus binding to CD4 cells, neutralization of HIV infectivity, and binding of purified gp120 to solid-phase sCD4), we generally observed additive effects or slight synergism between antibody and sCD4 in inhibiting gp120-CD4 interaction. We used a fourth assay to measure the irreversible inactivation of HIV infectivity by sCD4, a property that can also be mediated by antibody but with considerably less potency than sCD4. The reduction in HIV infectivity mediated by mixtures of sCD4 and antibody was always equal to or greater than the arithmetic sum of the reductions by either agent alone. The relevant antiviral effects of sCD4 and anti-HIV sera may include reversible blockage of receptor binding, irreversible inactivation of HIV infectivity, and in the case of antibody, additional reactions that are independent of receptor binding. Although predictions concerning the in vivo situation are speculative, we find no evidence in vitro for antagonism between sCD4 and antibody with respect to the net effect of the two in blocking HIV binding and infectivity.
Asunto(s)
Antígenos CD4/metabolismo , Linfocitos T CD4-Positivos/microbiología , Anticuerpos Anti-VIH/inmunología , Proteína gp120 de Envoltorio del VIH/metabolismo , VIH-1/metabolismo , Sueros Inmunes/inmunología , Unión Competitiva , Sinergismo Farmacológico , VIH-1/inmunología , VIH-1/fisiología , Humanos , Masculino , Pruebas de NeutralizaciónRESUMEN
A soluble form of the human CD4 glycoprotein (sCD4), the cellular receptor for human HIV, was treated with various physical, chemical, and enzymic regimens and tested over a range of concentrations for its capacity to inhibit the binding of HIV to CD4+ T cells. Reduction of disulfide bonds and alkylation in denaturing buffer (8 M urea) destroyed the inhibitory activity of sCD4, whereas reduction and alkylation in PBS had no effect. Derivatization or digestion of carbohydrate groups by periodate oxidation or by glycolytic enzyme digestion did not affect sCD4 inhibitory capacity. Digestion with trypsin or endoproteinase Glu-C destroyed activity. A limited digestion of sCD4 with endoproteinase Glu-C resulted in a mixture of fragments, however, and the mixture had inhibitory activity equivalent to that of intact sCD4. Within this mixture, a fragment of 23 kDa was identified that binds to HIV. Although sCD4 can be digested to yield fully active fragments, the requirement for intrachain disulfide bonding indicates that the minimum sized portion of CD4 that will retain full affinity for HIV will have to be formulated with a proper tertiary structure.