Rescue of HIV-1 broad neutralizing antibody-expressing B cells in 2F5 VH x VL knockin mice reveals multiple tolerance controls

J Immunol. 2011 Oct 1;187(7):3785-97. doi: 10.4049/jimmunol.1101633. Epub 2011 Sep 9.

Abstract

The HIV-1 broadly neutralizing Ab (bnAb) 2F5 has been shown to be poly-/self-reactive in vitro, and we previously demonstrated that targeted expression of its VDJ rearrangement alone was sufficient to trigger a profound B cell developmental blockade in 2F5 V(H) knockin (KI) mice, consistent with central deletion of 2F5 H chain-expressing B cells. In this study, we generate a strain expressing the entire 2F5 bnAb specificity, 2F5 V(H) × V(L) KI mice, and find an even higher degree of tolerance control than observed in the 2F5 V(H) KI strain. Although B cell development was severely impaired in 2F5 V(H) × V(L) KI animals, we demonstrate rescue of their B cells when cultured in IL-7/BAFF. Intriguingly, even under these conditions, most rescued B cell hybridomas produced mAbs that lacked HIV-1 Envelope (Env) reactivity due to editing of the 2F5 L chain, and the majority of rescued B cells retained an anergic phenotype. Thus, when clonal deletion is circumvented, κ editing and anergy are additional safeguards preventing 2F5 V(H)/V(L) expression by immature/transitional B cells. Importantly, 7% of rescued B cells retained 2F5 V(H)/V(L) expression and secreted Env-specific mAbs with HIV-1-neutralizing activity. This partial rescue was further corroborated in vivo, as reflected by the anergic phenotype of most rescued B cells in 2F5 V(H) × V(L) KI × Eμ-Bcl-2 transgenic mice and significant (yet modest) enrichment of Env-specific B cells and serum Igs. The rescued 2F5 mAb-producing B cell clones in this study are the first examples, to our knowledge, of in vivo-derived bone marrow precursors specifying HIV-1 bnAbs and provide a starting point for design of strategies aimed at rescuing such B cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antibodies, Neutralizing / immunology*
  • B-Lymphocytes / immunology*
  • Cell Separation
  • Enzyme-Linked Immunosorbent Assay
  • Flow Cytometry
  • Gene Knock-In Techniques
  • Genes, Immunoglobulin / genetics
  • Genes, Immunoglobulin / immunology
  • HIV Infections / immunology*
  • HIV-1 / immunology
  • Immune Tolerance / immunology*
  • Immunoglobulin Variable Region / genetics
  • Immunoglobulin Variable Region / immunology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic

Substances

  • Antibodies, Neutralizing
  • Immunoglobulin Variable Region