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In contrast to MN receptors, Pr1 and Pr2 antigens of isolated glycoprotein of erythrocytes are not inactivated by acylation of free amino groups. By introduction of easily leaving groups, e.g. trifluoroacetic residues, inactivation of the MN activity can be made reversible. No differences between Pr1 and Pr2 antigens could be found with the reactions described in this paper. Acylation m aqueous phase (buffer/anhydrous acetic acid) and m organic phase (pyridine/ anhydrous acetic acid) gave identical results qualitatively and quantitatively. It was not possible to split the N-acetic binding neither under mild alkaline conditions nor with aminoacylase. 4-5 amino groups out of 11 could be acylated, whereas succinylation in aquous phase (buffer/ anhydrous succinic acid) resulted in modification of only one free amino group, the calculations being based on a molecular weight of 30 000. Following succinylation MN activity was also lost, whereas the antigenic activity of Pr1 and Pr2 remained unchanged. The appearance of a negative charge instead of the positive charge of the free amino group on the glycoprotein did not affect Pr1 or Pr2 activity m any way. If glycoprotein was esterified under conditions which cause esterification of free sialic acid to a wide extent neither MN activity nor Pr1/Pr2 activity was altered. [ABSTRACT FROM AUTHOR]

Red cells sensitized with naturally occurring or 'immune' fowl antibody were lysed by fresh fowl serum. This fowl complement could not be replaced by that of human, rabbit or guinea pig. Both naturally occurring and 'immune' antibodies to red cells in the mammalian species tested did not lyse with fowl complement. Lysis by fresh fowl serum of sheep red cells sensitized with mammalian antibody is due to the presence of naturally occurrent antibody to these cells in the fowl serum; the enhancement of this lysis by the mammalian antibody will be described more fully in the next paper. Naturally occurring antibody to sheep red cells present in turkey serum and 'immune' antibody to fowl red cells were not lytic with fresh turkey serum, with fowl complement, with guinea-pig complement or with any combination of these. Some properties of fowl complement are given. [ABSTRACT FROM AUTHOR]

Whilst the ability of isoantibodies to agglutinate mouse red cells in saline medium does depend in part upon the properties of the antibody molecules, the concentration of antigen upon the red cell and certain genetically determined properties of the cell surface are of even greater importance. The red cells of mice of any strain will give positive results in the human serum:dextran system whilst reactions in a saline medium are unusual. In this paper the term ‘incomplete antibody’ is used to denote antibodies that can only be detected in conjunction with other antibodies in the human serum:dextran system. The time of appearance of antibodies to homografts of an ascites sarcoma, an ascites leukosis and a solid mammary carcinoma has been studied. Incomplete antibody as defined above has been detected by two methods. In the blocking test incomplete antibody is allowed to react with red cells before contact with complete antibody, a positive result being observed as a fall in titre when the treated red cells are subsequently exposed to complete antibody. In the second type of test, the synergic test, incomplete antibody is mixed with suitably diluted complete antibody and fitrated against suitable red cells, a positive result being a significant rise in titre as compared with complete antibody mixed with normal serum. Antibodies produced by the antigen donors did not give significant blocking or synergic effects. Incomplete antibodies are sometimes detectible on the third day and with regularity on the fourth day. Antibodies ‘complete’ for A strain red cells may appear at any time from the fifth day onwards. There is sometimes a drop in fitre of varying duration on the sixth day. This corresponds with the commencement of marked inflammatory changes on the graft bed. The maximum titre is attained at about two weeks. Antibodies may disappear in under three months or persist as long as a year. The function of antibodies in homograft reactions varies with the target tissue. However, they appear before the onset of anatomical signs of homograff response regardless of the type of target cell. [ABSTRACT FROM AUTHOR]

This article presents the study of canine erythrocyte antibodies. An adaptation of the Polybrene technique for typing of canine erythrocytes is reported in this paper. Dog whole blood was anticoagulated with acid-citrate-dextrose in a proportion of 1:9 The samples were stored at 40, and used within 10 days. Manual typing and titrations were performed. Adaptation of this technique to canine blood study required two modifications: 15 per cent bovine serum albumin was substituted for homologous normal serum; the concentration of Polybrene was reduced to 0.033 mg/ml. Results demonstrated that the Polybrene technique is from 12.5 (anti-A) to 3200-fold (anti-He) more sensitive than the manual technique.