Tokushukai Medical Group

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Pediatric Diseases: Blood Disease (3), mother-child immunity comes to an issue – Neonatal Allogeneic Immune Thrombocytopenia (NAIT)

Thrombocytopenia caused by mother-child incompatibility.

Thrombocytopenia can be seen in the newborn baby. Neonatal Allogeneic Immune Thrombocytopenia (NAIT) means the thrombocytopenia caused by mother-child incompatibility of man platelet specific antigen (HPA). It may be concerned that, at the idiopathic thrombocytopenic purpura (ITP) complicated pregnancy (expected mother who is complicated with ITP or SLE), platelet self-antibody which mother have is transferred to neonatal, so that it may develop thrombocytopenia in neonatal or newborn, neonatal, who is born from this kind of mother, platelet may not reduce, or even decreased a little. On the other hand, when remarkable platelet decrement observed, NAIT development should be considered because of the production of allogenic HPA antigen in mother’s body.

Recognize platelet antigen come from father as non-self.

As the same as Red Blood (Rh, ABO) type mother-child incompatible pregnancy, mother recognize the platelet antigen from father as non-self. Mother produced anti HPA-IgG antibody goes through placenta then is combined with neonatal platelet. Neonatal platelet which is sensitized by antibody is caught and destroyed in reticuloendothelinical of the spleen. In case when antibody infinity or value of the force I s strong, not only platelet but also megakaryocyte is destroyed. Amongst platelet allogeneic antigen HPA-3 and HPA-5 are considered as involved with NAIT. Normal hospital is unable to test HPA so that it is necessary to consult with Blood Center.

Fatal risk exists, such as intracranial bleeding.

Because of the decrease in platelets after delivery, it becomes easy to bleed, and the causes for lethal cerebral bleed, perforated encephalopathy or hydrocephalus. As neonatal splenic function becomes active after the delivery than before the delivery, platelets number will decrease further on 3rd day after birth than immediately after birth.

In case rapidly increasing platelets condition is obtained, prognosis is better, but in case numbers of platelets continues at less 10,000/µL, risks for alimentary canal bleeding or intracranial bleeding is becoming high.

Important issue in the diagnosis is the existence of allogeneic HPA antibody in maternal blood.

The most important issue in diagnosis is to prove the existence of allogeneic HPA antibody in maternal blood. Diagnosis criterion is; (1) There is no ITP in maternal body, and neonatal is accompanied by transient thrombocytopenia, (2) thrombocytopenia can be seen often on 1st child, (3) Infection, or other neonatal purpura, (4) Allogeneic HPA antibody, which reacts to neonatal platelets, is proved its existence in maternal blood serum

Immune globulin (IVIG) or steroid is used for the treatment according to ITP. Also, antigen-compliant platelet preparation or cleaning platelet preparation of maternal origin is considered desirable for platelet transfusion, but in case they are unavailable, platelet transfusion by random donar is possible as well.