Studies with Marked Antisera 2. Variation in the Specific Adsorption by Red Cells from Different Rabbits of One ¹³¹I-marked rabbit ISO-Antiserum

Abstract

Summary1. An apparently pure rabbit iso-antibody marked with 131I has been shown to adsorb specifically to a greater extent on some rabbit cells than on others. This accords with previous evidence that the same iso-antibody exhibits a higher titre with the cells which are shown here to absorb more marked antibody than with those which adsorb less.2. Saturation of two of these red cell types by repeated application of fresh quantities of the 131I iso-antibody until no more is specifically adsorbed, suggests that the number of functional antigenic sites is six or seven times greater on the one than on the other cell.3. There is no apparent difference in the amount of 131I iso-antibody adsorbed by any one type of rabbit cell in comparative titrations using 3·3 % MgSO4.7H2O medium instead of normal saline.

Reaction of I-131 Trace Labeled Human Anti-Rh0(d) With Red Cells*†

“…The interpretation of the data obtained in these studies is based on the specificity of the I-131 bound to red cells (11)(12)(13). The effective exploitation of I-131 red cell isoantibodies depends on unequivocal evidence that the 1-131 taken up by the red cells represents the specific isoantibody and conforms with the known behavior of these antibodies.…”

“…In view of this evidence the results obtained in these studies have been converted to nitrogen through the use of the iodine to nitrogen ratio of the total fraction that was iodinated. Although these studies do not provide direct experimental verification for these assumptions, valid and useful information can be obtained from these relative values (12 Figure 3. The amount of I-131 bound to the red cells increases progressively from 40 C. to a maximum at 370 C. and then decreases markedly beyond 370 C.…”

“…Bours-nell, Coombs and Rizk (11) appreciated the possibilities offered by the I-13 1 protein label and tagged human anti-Rho(D) serum. They were able to use the labeled isoantibody to estimate the number of Rho (D) sites and the Paul-Bunnell sites on the red cell, and more recently the antigen sites on the rabbit red cell (12). Melcher, Steinfeld and Reed (13), using both I-131 sheep red cell agglutinating rabbit serum and an I-131 incomplete red cell antibody, obtained from a patient with acquired hemolytic anemia, were able to show by zone electrophoresis that the red cell isoantibody activity was associated with the gamma globulin fraction.…”

Factors Influencing the Agglutinability of Red Cells. Variation of the Red Cells of the Rabbit in Susceptibility to Agglutination by Homologous Iso-Antisera

“…One obvious explanation for this variation was that the serum contained two antibodies; but since there was good reason to believe that it contained only one (Heard, 1955), it seemed that there might be something in the structure of the red cell which allowed one cell to agglutinate better than others, and this hypothesis was considered.…”

“…During the preparation of the sera which allowed four antigens temporarily labelled Z, Y, X and W to be recognized, the cells of a panel of rabbits were titrated against a number of different iso-antisera (Heard, 1955). Fig.…”