Correlation of canine secretory alloantigens A and Y with two fucolipids isolated from dog intestines.

Abstract

Previous studies have shown the presence in dogs of a polymorphic immunogenetic system which was defined as the canine secretory alloantigen alloantibody system (CSA) (1). This system involves the presence of alloantigens in most secretions and of the corresponding naturally occurring alloantibodies (2, 3). As in the human ABO system there is a mutually exclusive relationship between the presence of the antigen(s) and the corresponding antibodies. Three antigens have been detected so far: CSA A, which is cross reactive with human blood group A antigen (4), CSA X, and CSA Y (3). Concurrently, biochemical studies performed on dog individual small intestines have led to the isolation of fucose containing glycolipids with A, H-like, and Leb-like activity (5-7). The purpose of the present study was to investigate the correlation between CSA alloantigens and the glycolipid fractions isolated from dog small intestines. Materials and Methods. The isolation of the fucolipid fractions was performed on individual small intestine mucosa from six dogs selected for their different CSA types: dog 8(A), 15(X), 18(Y), 2(AX), 10(AY), and 3(XY). CSA typing was done with the immunofluorescence (IF) indirect technique on small intestine frozen sections using natural anti-CSA monospecific alloantisera as previously reported (1, 3). For shipment convenience the mucosa was transformed into dry acetone powder. The glycolipid fractions were prepared by a method described previously (5, 8, 9). The method involves extraction of fresh tissue with alcohol/ether 3: 1 (modified to alcoho1:ether:water 3:1:0.24 for use with acetone powder) and purification of the extracted lipids in chloroform solution with aqueous MgC12. The lipids were then fractionated by silicic acid column chromatography, solvent partition, Florisil column chromatography, dialysis, and finally thin layer chromatography (TLC) using system B (5). This system gives three groups of glycolipids (S), the fucolipids being the slowest migrating compounds. The fucolipids were eluted from the gel, taken to volume and the total sugar content determined by anthrone. An aliquot of the preparation was dried and taken up in saline for immunologic study in a concentration of about 1 mg/ml (using an approximation: 4 pmoles anthrone “galactose” equal 1 mg fucolipid). The fraction from dog 10 (type AY) was additionally made up in a concentration of 2 mg/ml. Another portion of the preparation was examined in TLC with three solvent systems: A, B, and D (5).