Memory B Cells Are Necessary for the Adoptive Transfer of Murine Peanut Allergy

Abstract

We hypothesize that memory B cells are necessary and sufficient for the adoptive transfer of murine peanut allergy (PNA). Peanut-allergic donor C3H/HeJ mice (with similar anti-peanut IgE levels, symptom scores (SS) and temperature drops (dT) following intraperitoneal (IP) challenge with crude peanut extract (CPE)) were treated intravenously with either anti-CD20 or isotype control (IC) antibody for 18 weeks. Naïve, lethally irradiated recipients were given bone marrow (BM) and splenocytes (SPL) from either anti-CD20 or IC-treated donors. In a separate experiment, B cells (negatively selected, >96% pure) from SPL of peanut-allergic or naïve donors were injected into naïve, irradiated recipients with or without the addition of naive SPL. Sera were obtained from recipients on days 7 and 17 post-reconstitution, and recipients were challenged IP with CPE on days 8 and 18. Treatment of donor mice with anti-CD20 for 18 weeks significantly reduced B cell numbers in the blood (p<0.0001, >95% reduction) and the spleen (p<0.0001, >98% reduction) but did not affect IgE levels. Recipients (n=15) given BM and SPL from anti-CD20 treated donors were protected from developing anti-peanut IgE (p<0.0001), SS (p<0.0001), and dT (p<0.0001) compared to recipients (n=14) given cells from IC-treated donors. Recipients (n=9) given purified B cells from peanut-allergic donors plus naïve SPL developed significantly elevated anti-peanut IgE (p<0.001), SS (p<0.002), and dT (p<0.003) compared to controls. These results demonstrate that memory B cells are required but not sufficient for the adoptive transfer of murine PNA. Help from a yet-to-be-defined cell population(s) found in naïve SPL is required.