IgE and CD23 are associated with bexosomes.

<p>(A) Bexosomes were isolated from B cell cultures stimulated with anti-CD40± IL-4 or IgE as indicated. 1.2511 fold increase ±0.177SD between lanes three and four. Equal bexosome protein was loaded on each lane and the blot was probed with polyclonal anti-CD23. Blot was probed with anti-MHC class II or anti-CD9and the result is shown at the bottom of (A). (B) Exosomes from B cell cultures stimulated with anti-CD40 and IgE (All lanes). IL-4 stimulation is as indicated. Lanes 1 and 2 are bexosomes from WT mice, Lanes, 3 and 4 are bexosomes from CD23^−/− mice. Blots are representative of at least three independent experiments. (C) Graph represents fold difference in densitometry between anti-CD23 blots for anti-CD40/IL4 and anti-CD40/IL4/IgE.</p

Increased <i>in vivo</i> T proliferation with <i>i.v</i>. injected DCs incubated with bexosomes.

<p><i>In vitro</i> differentiated LPS activated DCs were incubated with bexosomes stimulated with IgE/Ag ICs plus 10 µgOVA, 10 µgOVA or 300 µg OVA for three days. DCs were harvested and equivalent cells were injected into mice AT with DO11 cells. Spleens were assessed by flow cytometry on Day 3. Percent DO11TgTCR+ cells out of total CD4+ T cells were plotted. *p>0.05; n = 5 per group.</p

Bexosome-induced antigen specific T cell proliferation is enhanced by IgE, only in the presence of CD23and in vivo IgE immune complex T proliferation is enhanced in ADAM10B^−/− mice.

<p>(A) B cell cultures were stimulated as in <i>Methods</i>. Stimulated B cells from either WT or CD23^−/− mice were pre-incubated ±IgE for 24 hours and then IgE/Ag ICs were added for an additional 24 hours. Bexosomes were isolated and cultured with purified Ag-specific DO11 T cells for 3 days. Proliferation was determined using a [3H]-thymidine pulse (<i>Methods</i>). (B,C) On day −1 WT or ADAM10^B−/− mice were adoptively transferred with Ag-specific DO11 T cells and on day 0 immunized with IgE/Ag ICs (<i>Methods</i>); on day 3, spleens were removed and examined for expanded Ag specific DO11⁺ CD4⁺ T cells by flow cytometry (B) or immunohistochemistry (C). *p>0.05, ***p>0.0005; n = at least five per group.</p