High-dose intravenous IgG infusion may be a focus of the attention as a treatment of ITP. However, it has been pointed out by several investigators that the therapeutic effect of IgG infusion was transient in most cases with chronic ITP. Therefore, high-dose IgG infusion has been performed successfully as a pretreatment for expected bleeding during surgical operation.
Our clinical experience with high-dose intravenous IgG infusion with PGF₂α in a pregnancy case with ITP is reported in this paper. This patient received prostaglandin F₂α as a delivery promoting agent, when her platelet counts had increased to almost normal level by the use of high-dose IgG infusion for five days.
She had a normal delivery without any abnormal bleeding episode after this regulatory treatment to produce suitable conditions for safety delivery in ITP patients, and the neonate did not show any abnormal findings including platelet counts in postnatal period.
It seems to be concluded that high-dose intravenous IgG infusion with PGF₂α is a useful therapeutic technique for ITP patient in pregnancy.

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A sandwich enzyme immunoassay method for measuring a platelet-specific protein, platelet factor 4 (PF4) was developed by mean of purified antibodies to PF4. The assay system consisted of polystyrene balls with immobilized antibody F(ab′)₂ fragments and the same antibody Fab′ fragments labeled with β-D-galactosidase from E. coli. The measurable range was from 30pg to 3ng of PF4 per each tube. The results obtained with the enzyme immunoassay correlated well with those of a radioimmunoassay (γ=0.952, y=0.954x+2.43; n=36). The plasma PF4 levels in healthy subjects were 6.4±1.4ng/ml (±1 SD).
The levels of PF4 in platelet rich plasma obtained by platelet apheresis were 14.7±1.5μg/10⁹ cells. Platelets contained large amounts of PF4, while, the levels of PF4 in red blood cells and lymphocytes were very low, confirming the previous findings that PF4 is localized mainly in blood platelets. The levels of PF4 in plasma of platelet concentrates processed 24hr before and stored at 22°C were high (3.22±1.43μg/ml).

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We recently found the first Japanese example of the Le(a-b-) Bombay phenotype. The propositus (Mr. Oka.) was a healthy 20-year-old male donor.
The red cells of Mr. Oka. failed to react with anti-A, anti-B, anti-A+B, anti-H (Ulex europaeus, Laburnum alpinum and Eel serum), the serum from an O^h_m (Row II) and with the sera from six other Oh donors. His Lewis phenotype was Le(a-b-).
Propositus' serum contained anti-A, anti-B and anti-H. His saliva did not inhibit anti-A, anti-B, anti-H, anti-Le^a and anti-Le^b.
Testing 823, 498 donors with anti-H (Ulex europaeus), we found 2 Bombay and 3 para-Bombay phenotypes (0.00024%, 0.00036 respectively). Thus the gene frequency of the h-gene was roughly estimated to be 0.0015.

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