Immunomodulating effects of intestinal absorbed maternal colostral leukocytes by neonatal pigs.

Intestinal absorption of fluorescein isothiocyanate-labelled maternal colostral leukocytes (FITC-CL) was studied in 49 neonatal colostrum-deprived (CD) pigs from nine Minnesota miniature sows. Within 2 h postfeeding (pf), maternal FITC-CL were absorbed from the sibling's digestive tract and migrated into blood. The peak appearance of FITC-CL in blood occurred in samples at 5 and 7 h pf. By 24 h pf, cells were detected in liver, lung, lymph nodes, spleen and gastrointestinal tissues. To confirm intercellular migration of FITC-CL, gastrointestinal explant cultures from neonatal CD pigs were used. Maternal FITC-CL were observed to intercellularly migrate in 24 to 48 h pf between duodenal- and jejunal-epithelial cells to lamina propria cells and submucosal spaces. Fluorescein isothiocyanate-labelled maternal colostral leukocytes were not absorbed via ileal explant cultures. Unlike FITC-CL, maternal FITC-peripheral blood mononuclear leukocytes (FITC-PBL) were not absorbed either in vivo or in vitro by gastrointestinal tissues. When maternal FITC-PBL were intravenously administered to siblings they were distributed in blood and organs similar to FITC-CL. Following exposure to FITC-labelled cells, treated- and mock (untreated)-pigs were compared on the basis of PBL proliferative responses to phytomitogens. Sibling CD-pigs fed maternal FITC-CL showed higher PBL T-cell responses to phytohemagglutinin (PHA) and concanavalin A (ConA), and a significant stimulation (p < or = 0.01) of B-cell responses to pokeweed mitogen (PWM). Pigs fed FITC-PBL showed little PBL responses to PHA, ConA and PWM over PBL from mock pigs. Similarly, the influence of noncellular constituents of colostrum were also assessed by proliferative studies.(ABSTRACT TRUNCATED AT 250 WORDS)