Studies on Canine Secretory Alloantigens (CSA)

In order to select monospecific naturally occurring anti-CSA alloantisera for CSA typing, sera from 241 dogs of known CSA types (A, X, Y, AX, AY, XY and O) were tested with the indirect immunofluorescent (IF) technique on colon sections from dogs carrying CSA A, × and Y only. Anti-A antibodies were detected in 89% of expected anti-A sera, anti-X in 61% of expected anti-X, and anti-Y in 88% of expected anti-Y. Only a few monospecific anti-CSA sera, of titers ≦ 1/16, could be selected for IF CSA typing: 12 anti-A (5%), four anti-X (1.6%) and six anti-Y sera (2.5%). Monospecific anti-CSA antisera of much higher titers were obtained by allogeneic and xenogeneic immunization with CSA extracts. Anti-CSA alloimmune sera, when obtained in adequately CSA typed dogs, are monospecific and need no further treatment. The monospecificity of the xenoimmune sera raised in rabbits and rats could only be achieved through absorption with digestive mucosa dry acetone powder obtained from dogs of adequate CSA types. The ability to produce anti-CSA xenoimmune sera appeared to depend on the CSA type of the immunizing extract and on the species selected for immunization. No significant discrepancies were observed between monospecific naturally occurring anti-CSA alloantisera, alloimmune and xenoimmune antisera when tested concurrently in 752 dogs. The distribution of the CSA alloantigens was investigated in various organs from 41 dogs. They were found in gastrointestinal mucosa, in salivary glands, in gall bladder mucosa, in pancreatic acini and in tracheobronchial epithelium. They were absent from kidneys, liver, spleen, lymphnodes, heart, lungs, thyroid and adrenals. The data obtained in two populations of 157 and 93 unrelated dogs are compatible with a four allelic system, with three genes controlling A, × and Y, and an additional silent gene. This was confirmed by segregation studies conducted in 213 offspring of 40 families from a closely bred colony of beagles, and in 79 offspring of 14 random families.