Iso-antibodies to red cell antigens in pigs' sera. 2. The incidence of iso-antibodies to red cell antigens in the sera of adult pigs

On examining the sera from 80 sows and 67 boars in the routine typing service carried out by the Blood Group Research Unit, no antibodies other than anti-A were found in the boars' sera while, in 26% of the sows' sera, other anti-red-cell antibodies were also found as well as anti-A. All these sows were bred to boars of the same breed as themselves. The sera of 50% of 24 sows which had produced litters affected with thrombocytopenic purpura and which were mainly bred to boars of different breeds than themselves also contained iso-antibodies.
Of these iso-antibodies, anti-Ea and anti-Eb were the most frequent and were also present at the highest titres. Anti-Ee, anti-Fa, anti-Ka, anti-Kb, anti-Kd, anti-La and anti-Lg were also found but usually at only low titres.     

The solubilization of the L and M antigens from sheep red cell membranes

The Lp, L1 and M antigens from sheep red cells were solubilized using the non-ionic detergent Triton X-100 in the presence of dithiothreitol. Recovery rates were improved when membranes were sonicated at 4 degrees C in the presence of the detergent; values in the range 16-25% (M) and 9-17% (Lp and L1) were achieved for recovery.     

Iso-antibodies to red cell antigens in pigs' sera 3. The effect of maternal red cell iso-antibodies on the red cells of piglets

The effect of the red cell antibody, anti-Ea, on the red cells of piglets in four litters was studied. Although the antibody was absorbed from the colostrum by all the piglets, it had little effect on their packed cell volume, haemoglobin and red cell counts, and no differences were noted between Ea-positive and Ea-negative piglets in the same litter, despite the fact that red cells of the former were positive for the direct Coomb's test for up to a week after birth.
Anti-Ea was not detected in the serum of Ea-positive piglets, all of it apparently being taken up by their red cells, unlike the Ea-negative ones, in whose serum anti-Ea could be detected for up to fifteen weeks of age.     

Quantitative measurement of red cell antigens with Groupamatic]

Groupamatic 360 can be adapted to the quantitative measurement of erythrocyte agglutination reactions. Here the authors give the necessary conditions to obtain the best sensitivity and the best reproductibility. They have considered globular suspensions, incubation of the erythrocyte antiserums mixtures, centrifugation, agitation, photometric measurement. As concerns the quantitative technique, we used the average peripheral measurement obtained in the twleve cuvettes of the same selected disc sector. The calibration is fixed to 50 mV for a non agglutinated red cell suspension and to 950 mV for albumin in a saline solution. In these conditions, the best discrimination is obtained for agglutination with measures between 400 and 800 mV. The maximum sensitivity is reached with reactions corresponding to 600 mV, that is to say in our selected conditions with 50% of free red cells. The choice of the zone between 500 and 600 mV enables to detect variations from 1.5 to 2% in an antibody solution concentration. This zone is particularly favorable for quantitative work. Although a part of these operations in this preliminary work were manually effected, the automatic centrifugation, agitation, photometric measurement and results print out make possible a large number of measurements with very satisfactory reproductibility conditions. Besides, these experiments pointed out some factors of improvement which will be helpful for the new 360 G Groupmatic equipments.     

Resting cell studies on formation of water-soluble red pigments byMonascus sp.

Summary A resting cell system was developed for the biosynthesis of soluble red pigments byMonascus. The medium contains glucose, glycine, ZnSO₄ and MnSO₄ in pH 7.0 MOPS buffer containing cycloheximide to prevent protein synthesis. The linear production observed over a period of at least four h was due to de novo polyketide synthesis and biological methylation, as shown by inhibition with cerulenin, iodoacetamide and ethionine. Production was inhibited by carbonyl reagents and stimulated by pyridoxamine suggesting that the conversion of endogenous intracellular orange pigments to extracellular red pigments involves Schiff base intermediates and vitamin B₆ a cofactor. The resting cell system was used to study the mode of action of nutritional effectors previously pinpointed by experiments with growing cells. The negative effects of high concentrations of phosphate and Mg⁺⁺ are due to inhibition of pigment synthase action, not to repression or inactivation of these enzymes. The positive effects of trace metals, especially Zn⁺⁺, are due to stimulation of growth and enzyme action, not to induction or stabilization of the synthases.     

Quantitative flow cytometric analysis of ABO red cell antigens.

A flow cytometry method has been employed to quantitatively compare the expression of A, B and H antigens on various red blood cells (RBC). The H substance was directly labelled by fluorescein-conjugated anti-H lectin and the A and B antigens by indirect staining first with monoclonal anti-A or anti-B antibodies followed by fluorescently, fluorescein (FITC) or phycoerythrin (PE), labelled anti-mouse immunoglobulin (Ig) antibodies. More than a ten-fold difference in cellular fluorescence intensity was found within each sample. Both the percentage and the mean fluorescence of the positive subpopulation for each antigen were determined. Each RBC population was characterized with respect to the expression of A, B or H antigen by a compound mean value that was the calculated product of these two parameters. The results demonstrated a reciprocal relationship between the compound means of A or B and H. The ratio of A/H or B/H was found to be most informative. Homozygotes for A or B had ratios of greater than 200 and greater than 30, respectively, while heterozygotes (AO or BO) had ratios of less than 5. This method could also distinguish between A1 and A2; RBC carrying the A1 phenotype (as determined by agglutination with anti-A1 lectin) showed a higher A/H ratio than those carrying A2. In contrast to the reciprocity in the expression of A (or B) and H found in RBC obtained from different individuals, a direct correlation was found in the expression of these antigens by individual cells within a given population.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevalence and specificity of some rare red cell pan-reactive alloantibodies against high frequency red cell antigens among hospitalized Saudi patients

Some patients'' sera react with all available donors'' red cells and a compatible donor is difficult or impossible to be found. These may either be due to a complex mixture of antibodies or the presence of alloantibodies against high-frequency antigens (HFAs). The aim of this study is to identify the prevalence and characteristics of antibodies to HFAs in Saudi Arabian patients. A total of 23 out of 172 000 patients who received blood transfusions had rare alloantibodies to HFAs at an incidence of 0.013%. Twenty-three patients suspected with pan-reactive alloantibodies against HFAs had their red cells tested using antisera to HFAs, while their plasma was tested against a selected panel of red blood cells with rare phenotypes. Anti-Ge2 antibody was found in the highest number of patients (56.5%), whereas anti-U, anti JK3, anti H, anti-RH 29, anti-hr^s, anti-Kn^a, anti-Ch, anti-Rg, anti-Yt^a, and anti-Cr^a antibodies were found in the remaining patients (43.5%). This study suggests that although antibodies such as anti-Ge2, anti- Kn^a, anti-Ch, anti-Rg, anti-Yt^a , and anti-Cr^a are not clinically significant, they cause a delay in the provision of compatible blood. Whereas, anti-U, anti JK3, anti H, anti-RH29 and anti-hr^s are clinically significant antibodies. An understanding of antibody characteristics to HFAs and the widespread use of the extended red cell phenotype and antibody identification panel will both be helpful for the diagnosis of these HFAs.