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 authors describe a patient with sporadic distal myopathy associated with reduced caveolin-3 in muscle fibers in which the muscle atrophy was restricted to the small muscles of the hands and feet. Gene analysis disclosed a heterozygous 80 G-->A substitution in the caveolin-3 gene that was identical to that of reported cases of elevated serum creatine kinase. This patient further demonstrated possible clinical heterogeneity of myopathies with mutations in the caveolin-3 gene.

The presence of Borna disease virus (BDV) in peripheral blood mononuclear cells (PBMC) of 100 blood donors from Sapporo and 72 blood donors from Tokyo was examined using nested reverse transcriptase/polymerase chain reaction amplification with specific-primers for BDV p24. Anti-BDV p24 antibodies in the plasma of the 100 blood donors from Sapporo also were studied by enzyme-linked immunosorbent assay and by Western blot. BDV RNA was detected in 3 (4.2%) of the 72 PBMC samples from Tokyo, and in 5 (5%) of the 100 PBMC samples from Sapporo. In contrast, anti-p24 antibodies were found in only 1 (1%) of the donors from Sapporo. These results suggest that BDV infection in humans may be more widespread than previously thought.

69:481-484). In this study, we revealed that monocyte CD36 cDNA from two type II deficient subjects was heterozygous for C478 and T478 form, while platelet CD36 cDNA of these subjects consisted of only T478 form. In a type I deficient subject, both platelet and monocyte CD36 cDNA showed only T478 form. Expression assay using C478 or T478 form of CD36 cDNA transfected cells revealed that there was an 81-kD precursor form of CD36, and that the maturation of the 81-kD precursor form to the 88-kD mature form of CD36 was markedly impaired by the substitution. The mutated precursor form of CD36 was subsequently degraded in the cytoplasm. These results indicate that the 478C-T substitution directly leads to CD36 deficiency via defects in posttranslational modification, and that this substitution is the major defects underlying CD36 deficiency. (J. Clin. Invest. 1995. 95:1040-1046

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.