title: B cell activation during HIV-1 infection. II. Cell-to-cell interactions and cytokine requirement.
abstract: This study examined the mechanisms underlying the intense activation of HIV-1-specific B cells observed in peripheral blood of HIV-1-infected subjects. Spontaneous in vitro synthesis of anti-HIV-1 antibodies, as well as total Ig production, were dramatically reduced by accessory cell, but not T cell removal. This fall was counteracted by addition of rIL-6, but not other cytokines, to monocyte-depleted cultures; moreover, antisera against IL-6 suppressed spontaneous anti-HIV-1 antibody synthesis in a dose-dependent manner. Although IL-6 apparently sustained HIV-1-specific B cell activation, no increase in serum IL-6 levels was observed; PBMC from seropositive subjects did not produce increased amounts of IL-6 in vitro, compared to seronegative controls, both spontaneously and in the presence of LPS stimulation; finally, no constitutive expression of IL-6 gene could be documented in freshly isolated PBMC. These findings indicate that IL-6 may play a central role in HIV-1-specific B cell activation in seropositive patients, and further stress the importance of this cytokine during HIV-1 infection.
authors.affiliation: Institute of Oncology, University of Padua, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Amadori
authors.forename: R
authors.initials: R
authors.lastname: Zamarchi
authors.forename: M L
authors.initials: ML
authors.lastname: Veronese
authors.forename: M
authors.initials: M
authors.lastname: Panozzo
authors.forename: A
authors.initials: A
authors.lastname: Barelli
authors.forename: A
authors.initials: A
authors.lastname: Borri
authors.forename: M
authors.initials: M
authors.lastname: Sironi
authors.forename: F
authors.initials: F
authors.lastname: Colotta
authors.forename: A
authors.initials: A
authors.lastname: Mantovani
authors.forename: L
authors.initials: L
authors.lastname: Chieco-Bianchi
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology*; D015152:Blotting, Northern; D002450:Cell Communication; D016207:Cytokines / Q000502:physiology*; D015870:Gene Expression; D006678:HIV / Q000276:immunology*; D015483:HIV Antibodies / Q000096:biosynthesis; D015658:HIV Infections / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics / Q000502:physiology; D008213:Lymphocyte Activation; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D016207:Cytokines; D015483:HIV Antibodies; D007375:Interleukin-1; D007376:Interleukin-2; D015850:Interleukin-6; D012333:RNA, Messenger; D015847:Interleukin-4