Browsing by Author "Yeh, Chen-Hao"

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    Germinal center entry not selection of B cells is controlled by peptide-MHCII complex density.
    (Nature communications, 2018-03-02) Yeh, Chen-Hao; Nojima, Takuya; Kuraoka, Masayuki; Kelsoe, Garnett
    B cells expressing high affinity antigen receptors are advantaged in germinal centers (GC), perhaps by increased acquisition of antigen for presentation to follicular helper T cells and improved T-cell help. In this model for affinity-dependent selection, the density of peptide/MHCII (pMHCII) complexes on GC B cells is the primary determinant of selection. Here we show in chimeric mice populated by B cells differing only in their capacity to express MHCII (MHCII+/+ and MHCII+/-) that GC selection is insensitive to halving pMHCII density. Alone, both B cell types generate identical humoral responses; in competition, MHCII+/+ B cells are preferentially recruited to early GCs but this advantage does not persist once GCs are established. During GC responses, competing MHCII+/+ and MHCII+/- GC B cells comparably accumulate mutations and have indistinguishable rates of affinity maturation. We conclude that B-cell selection by pMHCII density is stringent in the establishment of GCs, but relaxed during GC responses.
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    Immune checkpoint modulation enhances HIV-1 antibody induction.
    (Nature communications, 2020-02-19) Bradley, Todd; Kuraoka, Masayuki; Yeh, Chen-Hao; Tian, Ming; Chen, Huan; Cain, Derek W; Chen, Xuejun; Cheng, Cheng; Ellebedy, Ali H; Parks, Robert; Barr, Maggie; Sutherland, Laura L; Scearce, Richard M; Bowman, Cindy M; Bouton-Verville, Hilary; Santra, Sampa; Wiehe, Kevin; Lewis, Mark G; Ogbe, Ane; Borrow, Persephone; Montefiori, David; Bonsignori, Mattia; Anthony Moody, M; Verkoczy, Laurent; Saunders, Kevin O; Ahmed, Rafi; Mascola, John R; Kelsoe, Garnett; Alt, Frederick W; Haynes, Barton F
    Eliciting protective titers of HIV-1 broadly neutralizing antibodies (bnAbs) is a goal of HIV-1 vaccine development, but current vaccine strategies have yet to induce bnAbs in humans. Many bnAbs isolated from HIV-1-infected individuals are encoded by immunoglobulin gene rearrangments with infrequent naive B cell precursors and with unusual genetic features that may be subject to host regulatory control. Here, we administer antibodies targeting immune cell regulatory receptors CTLA-4, PD-1 or OX40 along with HIV envelope (Env) vaccines to rhesus macaques and bnAb immunoglobulin knock-in (KI) mice expressing diverse precursors of CD4 binding site HIV-1 bnAbs. CTLA-4 blockade augments HIV-1 Env antibody responses in macaques, and in a bnAb-precursor mouse model, CTLA-4 blocking or OX40 agonist antibodies increase germinal center B and T follicular helper cells and plasma neutralizing antibodies. Thus, modulation of CTLA-4 or OX40 immune checkpoints during vaccination can promote germinal center activity and enhance HIV-1 Env antibody responses.