Reactivity of T cells from women with antibodies to the human platelet antigen (HPA)-1a to peptides encompassing the HPA-1 polymorphism.
The human platelet antigen-1a (HPA-1a) is the most common alloantigenic target in fetal and neonatal alloimmune thrombocytopenia (NAIT). Treatment currently depends on the outcome in previous pregnancies. HPA-1 specific T cell responses were determined in 14 HPA-1a alloimmunized women during or after pregnancies affected by NAIT. Peripheral blood mononuclear cells were incubated with peptides encompassing the Leu33Pro polymorphism (residues 20-39 and 24-45 in both Leu33 (HPA-1a) and Pro33 (HPA-1b) forms) or control recall antigens in the presence of autologous sera and T cell proliferation was measured by (3)H-thymidine incorporation. Control antenatal and postpartum sera suppressed T cell proliferation and use of such sera was avoided. Most patients (86%) responded to the HPA-1a peptides with 64% also having weaker T cell proliferation to the HPA-1b peptides; 14% had no activity towards any peptide despite responding to control antigens. Administration of IVIG during pregnancy appeared to reduce T cell reactivity to HPA-1 peptides. Postnatal anti-HPA-1a T cell responses from women who had a severe history of NAIT (an intracranial haemorrhage in a previous fetus) were greater than those from women with a mild history. This assay may have the potential to predict disease severity if performed prior to or early in pregnancy.
Jackson
D J
DJ
Bristol Institute of Transfusion Sciences, International Blood Group Reference Laboratory, UK.
Murphy
M F
MF
Soothill
P W
PW
Lucas
G F
GF
Elson
C J
CJ
Kumpel
B M
BM
D016824:Antigens, Human Platelet / Q000235:genetics / Q000276:immunology*; D002455:Cell Division / Q000276:immunology; D000939:Epitopes / Q000276:immunology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D039661:Integrin beta3; D007518:Isoantibodies / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology; D011110:Polymorphism, Genetic / Q000235:genetics* / Q000276:immunology; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000276:immunology*; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
D016824:Antigens, Human Platelet; D000939:Epitopes; C061248:ITGB3 protein, human; D039661:Integrin beta3; D007518:Isoantibodies; D010446:Peptide Fragments; C083451:human platelet antigen 1b