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品系バックグラウンド:BALB/c
品系構築策略:
IgE/FcεR1を互いにタンパク質ドメインとしてヒト化され(即ち、IgE Fc段とFcεR1 α鎖のヒト化)、マウスのIgE Fab段とFcεR1 β・γ鎖を保留してキメラ型のIgE/FcεR1ヒト化マウスモデルを作製する。
品系説明:
研究の応用:
このモデルはアレルギー、ぜんそく(アレルギー鼻炎、アレルギー皮膚炎、食物アレルギー、慢性蕁麻疹)と他のIgEが介する疾患(好酸性食道炎、炎症性腸病など)を選別するための革新的な治療法に用いられ、IgEが介する免疫反応の転化性と予測性を高める。
モデルの検証:
IgE/FcεR1の体内研究の主な制限はFcεR1のマウス体内での細胞分布がヒトと違っていることである。マウスのFcεR1は単核細胞/DC、ランゲルハンス細胞または嗜酸粒细胞で発現しない。このモデルはヒト化IgE/FcεR1合成物を産生でき、FcεR1のマウス体内での細胞分布は人体での分布と似ている。
Figure 1. Analysis of human FceR1 expression in double humanized IgE/FceR1 mouse cells.
Left panel: Expression of hFcεR1 α-chain from bone marrow-derived cultured mast cells (BMMCs) in presence of murine IL-3, stem cell factor (SCF) and IL-6 (8 weeks treatment). Right panel: Expression of hFcεR1 on murine eosinophils in peripheral blood upon intravenous injection of eotaxin (2.4 nmol/kg).
Figure 2. Analysis of human IgE expression in serum of double humanized IgE/FceR1 mouse.
Human IgE in serum of mice sensitized and challenged with ovalbumin. (black column: treated; white column: untreated)
Figure 3. Functional data on double humanized IgE/FcεR1 model: Induction of mast cell degranulation by anti-IgE Ab. Mast cells were sensitized with human IgE overnight to load hFcεR1 receptors and degranulation was stimulated by cross-linking loaded receptors with anti-hIgE. β-hexosaminidase activity in cell supernatant was determined as a percentage of total β-hexosaminidase activity in cell lysates.
Conclusion: Mast cells from the humanized model bind human IgE and degranulate upon cross-linking. This is specific and not restricted to given antigen. This set of data validates the functionality of the IgE high-affinity receptor. It binds human IgE and triggers degranulation upon cross-linking.
Figure 4. Functional data on double humanized IgE/FcεRI model: Inhibition of mast cell degranulation by anti-IgE monoclonal Ab. Mast cells were sensitized overnight with human IgE in presence of indicated biologics. The cells were washed and stimulated with anti-IgE.
β-hexosaminidase activity in cell supernatant was determined as a percentage of total β-hexosaminidase activity in cell lysates.