HLA class I-eluted platelets as an alternative to HLA-matched platelets.
BACKGROUND
Alloimmunized refractory thrombocytopenic patients often require HLA-matched platelet transfusions. As the HLA system is very polymorphic, sufficient HLA-matched donors are not available for every patient.


METHODS
In vitro elution techniques with citric acid incubation of platelets at pH 3.0 showed that platelets lose expression of HLA, whereas platelet-specific glycoproteins are preserved. This technique was modified for clinical use. Random-donor platelet concentrates were incubated with citric acid, subsequently washed, and transfused to two patients.


RESULTS
Platelet-specific glycoproteins were unaffected, and HLA expression decreased generally to below 25 percent of the initial expression. One alloimmunized patient who was without compatible donors because of a rare HLA type underwent repeated transfusions with acid-treated platelets. In contrast to the results with random-donor platelet transfusions, posttransfusion increments up to 47 x 10(9) per L were obtained with acid-treated platelets, and profuse gastrointestinal bleeding was stopped, while multiple skin hemorrhages were resolved. No side effects were observed. A second patient developed a severe transfusion reaction without platelet increment after one transfusion with acid-treated platelets expressing 30 percent of the original HLA antigens. Further transfusions were not given.


CONCLUSIONS
Standardization of the acid elution technique and validation of the technique in patients is necessary. The results suggest, however, that HLA-eluted platelets prepared under specified conditions may gain a place in platelet transfusion therapy.
Novotny
V M
VM
Red Cross Blood Bank, Leidsenhage, The Netherlands.
Huizinga
T W
TW
van Doorn
R
R
Briët
E
E
Brand
A
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001792:Blood Platelets / Q000276:immunology*; D002951:Citrates / Q000494:pharmacology; D019343:Citric Acid; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D051379:Mice; D017713:Platelet Transfusion
D002951:Citrates; D015395:Histocompatibility Antigens Class I; D019343:Citric Acid