Red cell autoantibody production in utero: a case report.

BACKGROUND: Autoantibody production by the fetus is thought to be extremely unlikely. Only one possible case of in utero autoantibody production against red cells by the fetus has previously been described. STUDY DESIGN AND METHODS: A case of apparent red cell IgG autoantibody production in utero is reported. RESULTS: This was established by a positive direct antiglobulin test in a newborn infant without evidence of maternal alloantibodies or autoantibodies. There was no evidence of clinically significant hemolysis at the infant's birth. After 6 weeks, his direct antiglobulin test remained strongly positive. The infant thrived without evidence of hemolysis, and after 6 months the direct antiglobulin test was negative. CONCLUSION: The production of autoantibodies to red cells in utero is possible, though rare. This did not result in apparent hemolysis in this patient.

Cisplatin-induced nonimmunologic adsorption of immunoglobulin by red cells.

Antibodies to cisplatin, an extensively used anticancer chemotherapeutic agent, have been implicated previously as a cause of immune hemolytic anemia. Investigation of a suspected case of cisplatin-induced hemolytic anemia in a 40-year-old man demonstrated that IgG could be adsorbed nonimmunologically by reagent red cells in vitro. This phenomenon was found to be a source of possible error in the interpretation of studies identifying specific cisplatin antibodies. Furthermore, cisplatin was found to be capable of producing a positive direct antiglobulin test (DAT), owing to the nonspecific adsorption of immunoglobulin and complement in vivo. Although this finding did not result in acute hemolysis, it may cause confusion in the investigation of DAT-positive hemolytic anemias. We question whether previous reports of cisplatin-induced hemolytic anemia are accurate in their assessment that such hemolysis was mediated immunologically. Future studies of suspected cases of hemolysis induced by this drug should include serologic investigation adequate to demonstrate the presence of specific cisplatin antibodies. A positive DAT in such patients should not be considered proof of drug-induced immune hemolytic anemia.

Clinical significance of anti-Yt(b). Report of a case using a 51chromium red cell survival study.

Several published reports have documented the variable survival of Yt(a+) red cells (RBC) in patients with anti-Yt(a) as measured by 51Chromium (Cr)-labeled RBC survival studies. Similar studies with anti-Yt(b) have not been reported. A 51Cr-labeled RBC survival study was performed using Yt(b+) RBCs and a monocyte monolayer assay in a young hemodialysis patient who required chronic transfusion therapy and who had developed anti-Yt(b). The survival of the transfused RBCs was 100 and 93 percent at 1 and 24 hours, respectively, with a half life of 21 days at termination of the study (normal, 28 to 32 days). These results showed no evidence of rapid destruction of the Yt(b+) RBCs, indicating that this patient could be transfused safely with blood from Yt(b+) donors. Long-term survival of the 51Cr-labeled Yt(b+) RBCs was shortened moderately, however, a finding that correlated with a slightly abnormal monocyte monolayer assay test.

Review of cannabinoids and their antiemetic effectiveness.

Marijuana has been used for over 2 centuries. Its major psychoactive constituent, delta-9-tetrahydrocannabinol (THC) was isolated in 1964 and first used to control nausea and vomiting during chemotherapy in the 1970s. THC has cardiovascular, pulmonary and endocrinological effects as well as actions on the central nervous system. Alterations in mood, memory, motor coordination, cognitive ability, sensorium, spatial- and self-perception are commonly experienced. The precise antiemetic mechanism is unknown. THC and nabilone act at a number of sites within the central nervous system. Cannabinoids have also been shown to inhibit prostaglandin synthesis in vitro. In controlled clinical trials, THC is superior to placebo and prochlorperazine in antiemetic effectiveness. Effectiveness of THC correlates to a 'high' experienced by the patient. A variety of chemotherapy regimens respond to THC including high-dose methotrexate and the doxorubicin, cyclophosphamide, fluorouracil combination. Cisplatin is more resistant. Side effects are generally well tolerated but may limit THC use in the elderly or when high doses are administered. Nabilone, a synthetic cannabinoid, is also an effective antiemetic which is more active than prochlorperazine in preventing chemotherapy-induced emesis, including cisplatin-containing regimens. Side effects are similar to THC and may be dose-limiting. Levonantradol, another synthetic cannabinoid, is an effective antiemetic. It may provide more flexibility in the outpatient setting since it can be administered orally or intramuscularly. Most side effects are mild except for dysphoria which may be dose-limiting.

Effects of proteases and neuraminidase on RBC surface charge and agglutination. A kinetic study.

Electrophoretic mobility, membrane sialic acid content and agglutinability by "incomplete" antisera against Rh-o, hr' and k antigens were determined for red blood cells in the course of treatment with trypsin, ficin and neuraminidase. Neuraminidase gradually produces a slight to moderate agglutinability as it reduced surface charge density in proportion to the amount of sialic acid removed. Proteases acted in two distinct steps. The first stage is characterized by the cells rapidly becoming highly agglutinable and by the unmasking of new negative charge as the first half of the sialic acid is removed. In the second stage the cells show a slight gain in agglutinability as surface charge is removed in proportion to sialic acid removal as in the case of neuraminidase. Neuraminidase-treated cells are considerably less agglutinable than cells reduced to the same zeta-potential by protease treatment. The greater efficacy of proteases compared to neuraminidase in making cells agglutinable could be because they not only reduce surface charge density but also increase antigen-antibody bond strength, render antigens more mobile in the membrane to allow clustering in regions of cell to cell antibody bridging and remove glycopeptide chains which may be causing steric hindrance to antigen-antibody binding or to cell-cell contact.

Cell electrophoretic, membrane sialic acid and quantitative hemagglutination studies on some MN variants.

The group of conditions exhibiting diminished MN antigenicity, increased saline agglutinability, decreased electrophoretic mobility and reduced membrane content of sialic acid includes enzyme-treated cells, the hereditary MNSs variants Mk and Mg, En(a-) and the acquired condition of persistent mixed-field polyagglutinability. Here we report our studies on the above serological, chemical and biophysical properties of Mg, Mk and EnaEn? CELLS AND ON TWO ADDITIONAL HEREDItary variants, Miltenberger III and V, (Mi-III and Mi-V). The latter clearly fits into this group of conditions. On the other hand, Mi-III shows its kinship to the broad group of abnormalities of membrane glycophorin but it deviates from normal in the opposite direction. That is we find evidence of decreased saline agglutinability, increased electrophoretic mobility and of increased sialic acid content. Moreover, in the rare MsMi-III Mk phenotype, the opposing effects evident in the heterozygotes tend to balance out their serologic and physicochemical expressions in the double heterozygote.