IMMUNOHISTOCHEMICAL LOCALIZATION OF TRANSFORMING GROWTH-FACTOR-ALPHA IN SUCKLING PORCINE INTESTINE

The distribution of transforming growth factor-alpha (TGF alpha), a me mber of the epidermal growth factor (EGF) family, was studied immunohi stochemically in small intestinal tissues of suckling pigs which were 7, 14 and 21 days of age. TGF alpha immunostaining was similar in vill ous epithelium in all intestinal regions of all ages examined, and was diffuse throughout the epithelial cytoplasm and more prominent in the apical and brush-border regions of the cells. Cytoplasmic immunoreact ive TGF alpha was also identified in crypt epithelial cells; the patte rn and extent of immunostaining differed among intestinal regions and ages. Ln all cases, the relative number of TGF alpha-immunopositive cr ypt epithelial cells was fewer than the number of immunonegative cells within the compartment. In duodenal and jejunal segments, relative nu mbers of Immunopositive crypt epithelial cells were greater in 14- and 21- than in 7-day-old pigs. in all 7-day-old pigs, a relatively great er number of immunopositive epithelial cells was present in the jejuna l crypts than in the duodenal crypts. Intracellular TGF alpha immunost aining was present within Peyer's patches of distal jejunum and ileum, and is a previously unreported finding. The presence of TGF alpha imm unoreactive protein within small intestinal crypt epithelium has not b een previously described in any species, and maybe unique to suckling animals or, alternatively the porcine species, These data suggest that TGF alpha may be an endogenous and or the EGF receptor in suckling po rcine intestine. Increased expression of TGF alpha in suckling pigs du ring the period in which marked structural and functional changes occu r within the small intestinal mucosa suggests a role for this growth f actor in remodelling and maturation of the neonatal mucosa.