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The frequencies of HLA antigens were compared between 55 patients with and 38 patients without lymphocytotoxic antibodies formation after long-term platelet transfusions. Only HLA-B60 and B75 were found to manifest significant difference between these two groups. Patients with HLA homozygosity had a higher incidence of alloimmunization. Although most of the platelet alloantibodies were against HLA antigens of high frequency, the HLA-antibodies were induced at a rate different from the frequency of their corresponding antigens. The antibodies against the first and second HLA loci are of similar frequencies. In conclusion, the patients with HLA homozygous alleles have a higher incidence of platelet alloimmunization, and the antibody of certain specificities has higher rate of occurrence. These findings may be helpful in platelet-donor selection.

The gelatin particle agglutination (GPA) test specific for antibody detection of human T-cell lymphotropic virus type 1 (HTLV-1) was used to screen 500 blood donors and 5000 physical-checkup individuals at Veterans General Hospital-Taipei. The positive rate of physical-checkup individuals and the blood donors was 0.18% (9/5000) and 0% (0/5000) respectively. Among the 9 GPA positive specimens, eight were confirmed to be positive by western blot analysis and a prevalence rate of 0.16% (8/5000). Seven of the nine GPA positive samples were also positive by indirect fluorescent antibody test and two of them had indeterminate results. Since GPA is less expensive, relatively simple and convenient, we recommend that GPA could be used as screening test for HTLV-1 infection of blood donors, followed by western blot method as a confirmatory test in blood bank.

A male, full-term baby with thrombocytopenia was born by a G3P2A1 mother who was not associated with autoimmune disease. Platelet antibody screening was positive by using lymphocytotoxicity test, platelet suspension immunofluorescence test and solid-phase red cell adherence test. The identified HLA antibody was of A2 specificity. It was confirmed by testing the mother's and the baby's sera against the lymphocytes and platelets of 10 HLA-A2-positive donors. The possibility of platelet-specific antibody as the cause of neonatal alloimmune thrombocytopenia was ruled out by testing against platelets of 10 HLA-A2-negative donors and the known platelet-specific antigens utilizing immobilized, purified platelet glycoprotein as targets. The mother's serum reacted strongly with both the father's and the baby's platelets and lymphocytes. This neonatal thrombocytopenia was most likely due to the maternal HLA antibody, which was induced by her antecedent gestations.

Platelet antigens of platelet samples from 36 donors, frozen for different intervals, were evaluated by the platelet suspension immunofluorescence test (PSIFT). A, B, PLA1(HPA-1a) and various HLA antigens were tested by their corresponding antisera. The antigen could be detected in almost all the samples after one month of freezing. After 3 and 6 months, the platelet antigens could only be detected in 29.2% and 3.7% of the samples, respectively. There was no difference in decay of antigen expression among A, B, PLA1 and HLA antigens. When compared with the freshly prepared platelets, frozen platelets presented stronger antigen expression after 2 to 4 weeks of storage. This may suggest that the frozen platelets could be used for platelet crossmatching procedures without loss of their antigenicity within one month.

Lymphocytotoxicity test (LCT) and platelet suspension immunofluorescence test (PSIFT) were used together to screen platelet-associated antibodies in patients who received long-term platelet transfusion. Twenty-four of 53 patients (45.3%) were immunized subsequently. Since the concordance of LCT and PSIFT was 100%, most of the platelet associated antibodies were of HLA specificity, and platelet specific antibody alone (in absence of HLA) was not detected. The identified antibodies were anti-A2, A11, A24, B5, B46, B57, B60, and B62. The majority of them were against the high frequency HLA antigens in the Chinese population. The development of antibody could not be correlated with the number of platelet-donors exposed, the time interval after the initiation of platelet transfusion, or the percentage of reactive lymphocytotoxic panels. HLA antibody was the major factor in causing platelet alloimmunization in the Chinese patients. However, some other unknown factors should be looked for. In addition, ABO incompatibility did not affect the posttransfusional increment while the platelet was compatible with LCT crossmatching.

Twenty-three patients with leukemia and ten patients with aplastic anemia who needed long-term platelet transfusion were regularly screened for platelet associated antibodies by a combination of platelet suspension immunofluorescence test (PSIFT) and lymphocytotoxicity test (LCT). Subsequently 13 of the patients (56.5%) with leukemia and 7 of the patients with aplastic anemia (70%) became alloimmunized. The overall incidence was 60.6% (20/33). The concordance of PSIFT and LCT was 100%, suggesting that all the platelet associated antibodies were of HLA specificity. The identified antibodies were anti-A2, A11, A24, B5, B40, B46, B57, B60 and B62. Most of them were antibodies against the high frequency HLA antigens in the Chinese population. There was no dose-response relationship in the development of alloimmunization. The interval between the initiation of platelet transfusion and the development of antibody varied from 10 to 192 days. The immunization is of all or none response. In our study group, about 40% of the patients who did not develop alloantibody within six months will never do so. We concluded that platelet transfusion should not be withheld for fear of alloimmunization and that HLA matched or lymphocytotoxic compatible platelet-donors may be helpful to alloimmunized patients.

An average of three (range 0-22) perfect matches for 65 patients could be found in 1490 filed HLA-typed donors. It could increase to 8.7 (0-45) if strong cross-reactive antigens were added. Three methods of platelet crossmatching, i.e, lymphocytotoxicity test (LCT), platelet suspension immunofluorescence test (PSIFT) and solid phase red cell adherence test (SPRCA), were used to search for compatible donors. Forty episodes of apheresis platelet transfusion were evaluated in seven patients. Using one-hour posttransfusional corrected count of increment (CCI), greater than 7500 microliters as a guideline to assess the reliability of these three methods, we found that the efficiency of PSIFT, LCT and SPRCA were 67.5%, 97.5% and 97.5% respectively. Retrospectively, we did the HLA-A, B typing of those matched donors. There was no significant difference in CCI among different HLA match grades. The concordance of LCT and SPRCA was 100%, indicating that all the antibodies were of HLA specificity and there was no platelet specific antibody. We concluded that HLA donor-file and platelet crossmatching technique could be used together in selecting suitable donors for alloimmunized patients.

Cytomegalovirus (CMV) infection is serious to immunocompromized individuals such as recipients of bone marrow transplantation, preterm infants and other immunosuppressed patients. Since there is no effective treatment as yet, prevention is the most effective way so far to avoid CMV infection. Blood transfusion is one of the dangerous sources and screening for CMV negative donors is mandatory, therefore, to provide blood components for immunocompromized patients. We have screened 2,015 donors at various ages for CMV antibody by using passive latex agglutination test (PLA). The results showed that the CMV antibody positive rate was 91.7% in Taiwan. It differs from those of the western countries (40-79%) and the countries of Africa and Asia (96-100%). It has also shown that the positivity rate is closely related to the age of donors. The seronegative rates of ages among 18-20, 21-30, 31-40, 41-50 and 51-60 years old were 10.7%, 9.8%, 3.9%, 1.2% and 0% respectively. It has suggested thus that the older the donor is, the higher the seropositive rate will be. Therefore, we should choose the donors of younger age as candidates for making CMV negative donor file.

We report six cases of chronic manganese intoxication in workers at a ferromanganese factory in Taiwan. Diagnosis was confirmed by assessing increased manganese concentrations in the blood, scalp, and pubic hair. In addition, increased manganese levels in the environmental air were established. The patients showed a bradykinetic-rigid syndrome indistinguishable from Parkinson's disease that responded to treatment with levodopa.