[Autoimmune-alloimmune neonatal neutropenia. Serum reactive IgG and neutrophil-specific phenotype detected by flow cytometry].
Auto or alloantibodies reactive with neutrophils define immune neutropenia. Alloimmune neonatal neutropenia is caused by maternal sensitization to paternal neutrophil antigens, resulting in IgG antibodies that are transferred to the fetus through the placenta. We present the studies in 4 children from 3 families with neutropenia of unknown origin (two of them were brothers). They were evaluated by flow cytometry in parallel with leukoagglutination. Reference values were established for serum reactive IgG in healthy volunteers for three dilutions (1/2, 1/5 and 1/20), both for the autologous reaction (serum and cells of the same individual) and for the heterologous reaction (serum and cells of different individuals). Results were expressed by an index defined by the quotient of the mean fluorescence intensity of the patient's serum divided by that of the reference serum. Serum reactive/agglutinant factors and circulating immune complexes were evaluated in patients and parents serum. Neutrophil specific phenotypes were determined for HNA-1a, HNA-1b and HNA-2a. Reactive IgG/agglutinant factors were found in 4 children. Two maternal sera were reactive against paternal and/or children neutrophils. Circulating immune complexes were detected in 2/4 children sera and were negative in 3/3 maternal sera. Maternal/children incompatibility was detected in the four cases. The three mothers had the same phenotype: homozygous NA1/NA1, NB1+.
Riera
Norma E
NE
lnstituto de Investigaciones Hematológicas, Academia Nacional de Medicina, Buenos Aires, Argentina. nriera@hematologia.anm.edu.ar
Kantor
Gustavo L
GL
Khoury
Marina
M
Nucci
Rodrigo Parias
RP
Rapetti
Maria Cristina
MC
Aixala
Monica
M
Goldsztein
Sofia
S
Flores
Gabriela
G
de Bracco
Maria M de E
MM
D000371:Agglutination / Q000276:immunology; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood / Q000276:immunology*; D004804:Eosinophils / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D016179:Granulocyte Colony-Stimulating Factor; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D007958:Leukocyte Count; D008297:Male; D009503:Neutropenia / Q000097:blood / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism; D010641:Phenotype; D011247:Pregnancy; D011994:Recombinant Proteins; D012016:Reference Values
D019268:Antibodies, Antineutrophil Cytoplasmic; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D016179:Granulocyte Colony-Stimulating Factor