Antibody repertoire against HIV-1 gp120 triggered in nude and normal mice by GM-CSF/gp120 immunization Gustavo del Real, Mercedes Llorente, Pilar Lucas, Leonor Kremer, Jose L. ToraÂn, Carlos MartõÂnez-A* Department of Immunology and Oncology, Centro Nacional de BiotecnologõÂa, UAM, Cantoblanco, Madrid, E-28049, Spain Accepted 22 July 1999 Abstract Granulocyte±macrophage colony stimulating factor (GM-CSF) facilitates the induction of primary immune responses by activating and recruiting antigen-presenting cells (APC), which eciently present antigen determinants to Th cells. We have derived a functional GM-CSF/gp120 chimeric protein that, following immunization in soluble, adjuvant-independent form in normal mice, triggers highly speci®c, high anity anti-gp120 antibodies. In contrast, nude mice respond with mutated, polyreactive, low anity antibodies that mature further and increase in anity in T cell-reconstituted nude mice. Anti-gp120 antibody production in nude mice is mediated principally by GM-CSF/gp120-triggered IL-4 production, since neutralizing anti- IL-4 abrogates the in vivo response. The anti-gp120 antibody response in normal, nude and T cell-reconstituted nude mice is encoded at a remarkably high frequency by the VH81X and VH7183 genes, a family used notably during fetal life and, when expressed at the adult stage, associated with autoimmune disease. We conclude that HIV gp120 binds and selects a subpopulation of developing B cells expressing a set of VH genes associated with immunode®ciency and autoimmunity. # 1999 Elsevier Science Ltd. All rights reserved. Keywords: HIV-1/7183 VH gene; Antibody; Nude mice 1. Introduction GM-CSF is a hematopoietic factor that leads to the proliferation and dierentiation of hematopoietic pre- cursor cells to neutrophils, eosinophils and macro- phages (Gough et al., 1984; Metcalf, 1981). It is also the main stimulatory cytokine for Langerhans and dendritic cells (Sallusto and Lanzavecchia, 1994), the most important cell types for the stimulation of in vivo primary T cell-mediated immune responses (Steinman, 1991). GM-CSF also enhances monocyte surface expression of MHC class II, adhesion mol- ecules and costimulatory factors, and stimulates IL-1 secretion, relevant for antigen presentation to T lym- phocytes (Smith et al., 1990). GM-CSF has been shown to enhance T cell prolif- erative responses to suboptimal antigen concentrations and to augment primary antibody responses (Morrisey et al., 1987; Grabstein et al., 1986; Disis et al., 1996; Kim et al., 1997). Furthermore, GM-CSF can increase the immunogenicity of tumors in animal models (Drano et al., 1993) and cytokine-transduced, leth- ally-irradiated autologous melanoma cells have been used as a therapeutic vaccine in humans, resulting in the generation of an anti-tumor immune response as- sociated with clinical bene®t (Ellen et al., 1997). HIV-1 infection is associated with B cell hyperplasia, hypergammaglobulinemia, elevated autoantibody levels, circulating immune complexes, and phenotypic and functional changes in B cells resulting from in vitro activation (Schnittman et al., 1986; Pahwa et al., Molecular Immunology 36 (1999) 721±731 0161-5890/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S0161-5890(99)00090-5 www.elsevier.com/locate/molimm * Corresponding author. Tel.: +34-1-585-4544; fax: +34-1-372- 0493. E-mail address: cmartineza@cnb.uam.es (C. MartõÂnez-A) Abbreviations: GM-CSF, granulocyte±macrophage colony stimu- lating factor; APC, antigen-presenting cells; CDR, complementarity- determining region.