The relative frequencies and distribution of immunoglobulin-bearing cells in the intestinal mucosa of neonatal and weaned pigs and their significance in the development of secretory immunity.

A comparative immunohistochemical study has been made of cells containing immunoglobulins IgM; IgA and IgG in the intestines of pigs varying in age from 2 days to 12 weeks. Cells with cytoplasmic IgM appeared in the lamina propria earlier than those containing either IgA or IgG. The duodenum appeared to be the preferred site of infiltration, the numbers of cells occurring in duodenal mucosa were consistently higher than at other levels of intestine irrespective of immunoglobulin class. Igm cells formed the majority of immunoglobulin contained cells in the lamina propria of the small bowel in suckling pigs upto 4 weeks of age. But in the weaned animal the proportion of IgM cells gradually declined with maturity until by the time the pigs were 12 weeks old nearly 90 per cent of the cells contained IgA.