Objective: To assess whether lack of enteral feeding significantly impairs generation of specific immune responses to an acute viral infection.
Summary background data: Parenteral feeding provides adequate nutrients to meet metabolic needs, but lack of enteral stimulation creates a defect in mucosal immunity characterized by loss of IgA-mediated defenses in the respiratory tract.
Methods: The enzyme-linked Immunospot (ELISPOT) assay was used to determine accumulation of immunologic cells in the nasal passages after diet manipulation. Viral shedding and nasal IgA levels were measured in additional groups of mice.
Results: After determining the time course of antibody-forming cells (AFCs) via ELISPOT to an active infection with the A/PR8 influenza virus, a significant reduction was found in total AFCs, IgA-producing AFCs, and IgG-producing AFCs over the course of a 13-day experiment with significant depression in viral-specific respiratory IgA levels. Eight days following an active infection, seven of nine total parenteral nutrition-fed animals continued to have viral shedding in the nasal passages compared to one of nine chow-fed mice and one of six animals fed a complex enteral diet.
Conclusions: Lack of enteral stimulation significantly impairs the generation of IgA-mediated mucosal immunity.