[Platelet alloimmunization in patients with oncologic blood disorders treated with multiple transfusions: prospective study in adults and children].
BACKGROUND
Refractoriness continues to be a major complication of platelet transfusion therapy in patients with multiple transfusions. Despite most cases are secondary to non-immune causes, the most serious is that associated to alloimmunization. The incidence and consequences of HLA and non-HLA (platelet specific) antibodies are unknown in our country.


OBJECTIVE
To prospectively determine the frequency and characteristics of post transfusion alloimmunization and the incidence of platelet specific antibodies.


METHODS
Forty one adults and 24 children with a recently diagnosed malignancy and undergoing chemotherapy that required multiple transfusions were studied. Screening for antiplatelet antibodies (platelet membrane ELISA) was performed before the first transfusion, every four weeks or whenever the 1 hour corrected count increment for platelet transfusions was lower than 5000. Platelet specific antibodies were identified with a monoclonal antibody-specific immobilization of platelet antigens (MAIPA), with anti-GPIb, GPIIb/IIIa, GPIa/Iia and anti-HLA class I.


RESULTS
Adult patients received an average of 10.2 +/- 5.5 units of red blood cells and 58.6 +/- 35.4 units of platelets. Children received 4.8 +/- 3.7 units of red blood cells and 9.6 +/- 6.7 units of platelets. HLA antibodies appeared in 7 of 41 adult patients (17%), platelet specific alloantibodies were found in two patients (one anti GP Ia/IIa and one anti GP Ib). Platelet refractoriness appeared in three alloimmunized patients. No child had detectable serum antibodies during follow up.


CONCLUSIONS
Platelet transfusion refractoriness of immune origin occurs infrequently in our population and the presence of platelet antibodies does not mean that it will appear. The use of leukocyte depleted blood components to prevent refractoriness cannot be justified at this time.
Pereira
J
J
Departamento de Hematología-Oncología, Escuela de Medicina P Universidad Católica de Chile, Santiago. jpereira@osler.med.uc.cl
Bronfman
L
L
Bertín
P
P
Marzouka
E
E
Hidalgo
P
P
Amaya
S
S
Mezzano
D
D
D000293:Adolescent; D000328:Adult; D000368:Aged; D000741:Anemia, Aplastic / Q000276:immunology* / Q000628:therapy*; D000918:Antibody Specificity / Q000276:immunology; D016824:Antigens, Human Platelet / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006680:HLA Antigens / Q000276:immunology*; D006801:Humans; D007223:Infant; D007518:Isoantibodies / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D017713:Platelet Transfusion / Q000009:adverse effects*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000276:immunology* / Q000628:therapy*; D011446:Prospective Studies
D016824:Antigens, Human Platelet; D006680:HLA Antigens; D007518:Isoantibodies
Aloinmunización plaquetaria en pacientes onco-hematológicos politransfundidos: estudio prospectivo en adultos y niños.