Immunomodulatory effects of ovine serum immunoglobulin in the growing rat

This study aimed to determine whether orally administered ovine serum immunoglobulin (Ig) modulates aspects of immunity such as phagocytosis, lymphocyte proliferation, cytokine production, intestinal and plasma Ig concentrations in growing rats. Forty-five male Sprague-Dawley rats (n = 15/group) were used in the 21-day study, and fed a basal control diet (BD; no Ig) or two test diets: freeze-dried ovine Ig (FDOI) and inactivated ovine Ig (IOI). Phagocytic activity of peripheral blood leukocytes and lymphocyte proliferation in the presence of the mitogen concanavalin A (ConA) was greater (P < 0.05) for the FDOI-fed rats than for the BD- and IOI-fed groups. ConA-stimulated and unstimulated spleen cell culture produced higher (P < 0.05) interferon-γ and interleukin-4, respectively, from rats fed the FDOI than rats fed the BD diet. In the jejunum, ileum and plasma, rats fed FDOI produced higher (P < 0.05) concentrations of secretory IgA (sIgA) than rats fed IOI or BD. Rats fed the FDOI diet had greater jejunal (P = 0.037) and lower plasma (P = 0.025) rat IgG concentrations than rats fed either BD or IOI. In conclusion, an ovine Ig fraction selectively modulated various indices of immune function.