Number and distribution of IgM cells and IgA cells in colonic tissue of conditioned sex- and breed-matched dogs.

Colonic tissue from 3 male and 3 female Beagle dogs was stained for immunoglobulin (Ig)A and IgM cells. The colonic mucosa was divided vertically into 3 zones with an ocular reticule. The mean numbers of IgA and IgM cells and the mean percentages of the total number of the IgA or IgM cells were determined for each zone. (A comparison of IgM cell counts obtained by 2 investigators gave evidence that the results were consistent between different counters.) Comparison of the data from males with data from females showed that there was no difference for IgM cells, but that young, male dogs had more IgA cells that did old, female dogs in that portion of the colonic mucosa that was closest to the colonic lumen. The number and pattern of IgA cells were similar to those found in a previous study of IgA cells which used male, mixed-breed dogs, ie, there were fewer IgA cells in the lamina propria closest to the colonic lumen than in the deeper lamina propria. The distribution of IgM cells showed a similar nonuniform trend. Finally, there were fewer IgM cells than IgA cells in the deeper lamina propria; however, the percentages of the total number of IgA and IgM cells found in each zone were equivalent.