Intrinsic Factor/内因子

Intrinsic Factor

Diseases:
Pernicious Anemia 

Circulating antibodies against gastric intrinsic factor (IF) are highly specific and of high diagnostic relevance for pernicious anemia. Two types of clinically important autoantibodies can be measured: (i) so-called blocking antibodies which prevent the binding of vitamin B₁₂ to the IF molecule; they are present in >50% of all patients with Biermer anemia; (ii) other types of antibodies to IF may interfere with the binding of the IF-Vit B₁₂complex to the ileal receptor and are less common and sensitive.

Intrinsic factor is produced by DIARECT in the baculovirus / Sf9 insect cell expression system. This high-quality antigen is secreted from the insect cell along the endosomal pathway via Golgi glycosylation and passes into the culture medium. Endogenous bound cobalamin/vitamin B₁₂ is depleted during the purification process, exposing all relevant epitopes for autoantibody binding on the recombinant intrinsic factor.

相关疾病：恶性贫血

恶性贫血（PA）是一种自身免疫紊乱导致神经上的改变的疾病。包括痴呆和与缺乏维生素B12相关的贫血疾病。当出现内因子的自身抗体或者通过干扰胃壁细胞的吸收减少内因子的水平时，恶性贫血患者会发生缺乏维生素B12的症状。    抗胃内因子（IF）的循环抗体具有高特异性及与恶性贫血的诊断相关性。临床上可以坚测两种重要的自身抗体：（i）封闭抗体（阻止维生素B12结合内因子），在多于50%的恶性贫血患者体内可检测到；（ii）其他类型的内因子抗体，可能会干扰IF-Vit-B12复合物结合回肠受体，这种比较不常见，不太敏感。

DIARECT生产的内因子是在杆状病毒/Sf9昆虫细胞表达系统中表达。这个高品质的抗原是有昆虫细胞通过高尔基体糖基化经胞内通路分泌出来到培养基中的。内源结合的维生素B12在纯化过程中被去除，暴露出所有相关的表位供自身抗体结合。