Pre- and posttransfusion antibody titers were performed on 6 patients with anti-Sd^a transfused with incompatible blood. In 3 of these patients a significant rise in IgG antibody titer was found. The data suggest that in occasional patients the Sda antigen does evoke a secondary immune response. We evaluated 245 pregnant women for the presence of Sd^a and found that 30% were Sd(a-). This incidence was significantly higher than that found in normal blood donors (4%), but was lower than that described in previous reports. We found that 22% of pregnant women in their first trimester were Sd(a-) whereas at term 36% were Sd(a-). These significantly different incidences of antigen positivity suggest decreased antigen expression with progressing pregnancy, as seen in the Lewis system. No difference was found in the incidence of anti-Sd^a between pregnant women, either during their first trimester or at term, and normal donors.
A solid-phase kinetic enzyme-linked immunosorbent assay has been developed to measure binding of antibodies to purified or synthetic blood group antigens and tested in the Lewis blood group system. Chemically synthesized Lewis a antigen is used as the target for the binding of serum antibody in this sandwich-type assay. Kinetic, rather than endpoint, determinations are used to calculate the amount of specific antibody. Data are presented showing the assay to be quantitative, sensitive, and specific. It can separately quantitate the amount of IgG or IgM anti-Lewis a present in patient sera. The assay uses commercially available reagents and is semiautomated. Thus, it will be useful for studies in quantitative immunohematology as other blood group antigens become available in purified form.
Lewis blood group antibodies rarely, if ever, cause hemolytic disease of the newborn. This observation has been attributed to the absence both of Lewis antigens on fetal cells and of maternal IgG Lewis antibody. In the present study, sera from 13 mother-infant pairs were tested for the presence of anti-Lewis (a) by hemagglutination and by a sensitive and specific kinetic enzyme-linked immunosorbent assay. By routine hemagglutination methods, anti-Lea was present in all maternal samples but absent in all cord samples. By kinetic enzyme-linked immunosorbent assay, IgG anti-Lea was present in 13 of 13 maternal samples and in 12 of 13 cord samples. These results indicate that IgG anti-Lea antibodies are common and do cross the placenta. This suggests that they do not cause hemolytic disease of the newborn because of the low levels of Lewis antigens on fetal red cells.
Clinical features together with elevation of pancreatic enzymes are the key diagnostic indicators of acute pancreatitis. We report a case of a woman in her 50s who presented with abdominal distension and serum amylase raised to more than 30 times the upper limit of normal. She was initially treated for acute pancreatitis, however, she was not symptomatic of this and the pancreas appeared to be normal on CT scan. Further investigations revealed the patient had a high-grade serous ovarian carcinoma with nodal metastatic spread. An amylase-secreting ovarian tumour was suspected, which was supported by elevated salivary-amylase isoenzymes, consistent with previous reports in the literature. The patient was treated with chemotherapy and surgery, during which her serum amylase and CA-125 initially fell significantly, but eventually both increased, reflecting disease progression. This case serves as an important reminder to consider non-pancreatic causes of raised serum amylase, to avoid misdiagnosis.
The neutralization of antibodies to the Lewis blood group systems is important in confirming the presence of these antibodies and in investigating complex alloantibody problems. An improved method for neutralizing Lewis antibodies is described. Insoluble immunoadsorbents containing synthetic Lewis antigens are used to physically remove the antibody from serum. Thirty-five sera containing Lewis antibodies were neutralized completely using this technic; 23 non-Lewis alloantibodies were not inhibited. In contrast with current methods, this technic does not dilute the patient serum and results in an affinity purified serum sample.
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