Rh陰性の母親にAnti-Dを投与してもRh抗原に対する感作が起こらないのはなぜですか


1

私が理解しているように、抗Dは胎児のRh + RBCをコーティングします。これらはIgGでマークされているため、他のものの中で貪食されて破壊されます。

RBCが貪食される場合、その食作用で生成された抗原がリンパ球に提示され、Rh抗原に対する感作を引き起こす可能性はありませんか?

2

According to this 2006 review article:

In summary, the evidence indicates that prevention of RhD immunization by prophylactic anti‐D might occur both by rapid macrophage‐mediated clearance of anti‐D–coated RBCs and/or by down regulation of immature DCs or anti‐D–specific B cells before development of the anti‐D response occurs.

The author states that the macrophage-mediated clearance is most likely the predominant mechanism of prophaylactic anti-D's effects on maternal immune response. This is because "the flow of RBCs is predominantly through the red pulp (the site of destruction of IgG‐coated RBCs) and few RBCs enter the white pulp (areas of immune response generation)".

These [macrophage IgG Fc] receptors recognize cell‐bound IgG “labeling” target cells to which immunity has developed, mediating their accelerated phagocytosis and destruction. This is a noninflammatory process, avoiding unnecessary collateral tissue damage. Immune responses to blood‐borne antigens take place in the white pulp.

In other words, rapid clearance of anti‐D–coated RBCs by splenic macrophages in red pulp is non-inflammatory and will prevent a maternal (B-cell) immune response to RhD antigen.

Source:

  • Kumpel BM. On the immunologic basis of Rh immune globulin (anti‐D) prophylaxis. Transfusion 2006;46:1271‐1275.