Neonatal Alloimmune Neutropenia (NAIN) is a cause of neutropenia in neonates.


Synonym: Isoimmune Neonatal Neutropenia


Human neutrophil antigens: HNA-1a, HNA-1b, HNA-1c, HNA-1d, HNA-2a, HNA-3a, HNA-3b, HNA-4a, HNA-4b, HNA-5a, HNA-5b


Clinical features:

(1) NAIN can occur with a first pregnancy.

(2) NAIN often recurs in future pregnancies.

(3) The course of an affected pregnancy is often uneventful.

(4) The infant may be asymptomatic or can have recurrent infection.

(5) No other diagnosis can explain the neutropenia better.


Laboratories features:

(1) absolute neutropenia (< 1,500 per µL in first week, < 1,000 per µL from 2 to 26 weeks)

(2) normal red blood cell and platelet counts

(3) maternal antibodies to a neutrophil-specific antigen

(4) absence of the neutrophil antigen in the mother but presence in the father


Tests for detecting anti-granulocyte antibodies:

(1) GAT (granulocyte agglutination test)

(2) indirect GIFT (granulocyte immunofluorescence test)

(3) MAIGA (monoclonal antibody-specific immobilization of granulocyte antigen)


The neutropenia may last from a few weeks to 6 months, then the neutrophil count returns to normal.


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