Serum from a thrombocytopenic patient who was refractory to the transfusions of HLA-matched platelets
contained a platelet-specific alloantibody, anti-Nak^a. Immunofluorescence analyses revealed that the Nak^a antigen
defined by the serum was expressed exclusively on platelets and its distribution was different from P1^A1, Bak^a Yuk^a or
Yuk^b. Analysis by Dr. von dem Borne’s group revealed the Nak^a was also different from Ko^a, Ko^b or Zw^b. Family studies
showed that the Nak^a antigen was inherited as an autosomal codominant trait. Its antigen frequency in the Japanese
population was over 97%. The results of the enzyme immunoassay using monoclonal antibodies for antigen immobilization
showed that the Nak^a epitope did not appear to reside on GPIIb/IIIa or Ib. The transfusions of Nak^a-compatible
platelets improved the patient’s thrombocytopenia.
The effect of the diversion method on the frequency of bacterial contamination is robust. The low incidence of septic reactions after PC transfusion in Japan in spite of the contamination frequency being comparable to those in Western countries and the noninstitution of culture screening suggests the importance of a short shelf life (72 hr) for PCs introduced in Japan.
It has recently been shown that the Naka antigen, which is absent in 3% to 11% of Japanese blood donors, is expressed on platelet glycoprotein IV (GPIV; CD36) (Tomiyama et al, BLOOD, 75:684, 1990). In the present studies, flow cytometry was used to distinguish differences in the reactivity of Naka+ and Naka- platelets with both OKM5, a monoclonal antibody that recognizes an epitope on GPIV, and with polyclonal anti- GPIV antibody. OKM5 was also used to screen 871 platelet concentrates prepared from healthy US blood donors. Three of these showed markedly deficient binding of 125I-OKM5 or an incidence of 0.34%. Two of these donors were re-accessed and showed less than 1% binding of 125I-OKM5 as compared with 10,300 +/- 1,500 binding sites per platelet in controls (n = 4). Platelets from these two US donors were radiolabeled (125I, 3H) and compared with control platelets and with platelets from Japanese Naka+ and Naka- donors by crossed immunoelectrophoresis, protein blots, immunoprecipitation, and two-dimensional gel electrophoresis. GPIV could not be detected by any of these techniques in the Naka- platelets nor in the donors whose platelets showed deficient binding of OKM5. These results suggest that GPIV functions as an isoantigen rather than an alloantigen in immunizing Naka- platelet recipients. This is the first report of the absence of a major platelet membrane GP in healthy blood donors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.