Matthew Wheeler, Robert Harms, Virginia Hardie, Kristina Lorenzo, Natalie Targy, David Mercer, Nora Sarvetnick

Department of Surgery, University of Nebraska, Omaha, NE, United States

Introduction: The small intestine is an important part of the immune system, containing more immune cells than any other organ. Patients with Short Bowel Syndrome (SBS) from infancy are deprived of this organ that is essential for normal immune system development. It is our hypothesis that these patients have aberrant immune phenotypes due to the massive differences in their physiology. At our high volume center, practitioners who care for SBS patients have noted that these patients do not have immune responses typical of infants and toddlers.

Methods: Ten pediatric SBS patients were identified and parents underwent consent for study. Patient characteristics: 6mo to 4yrs of age, TPN dependent, small bowel length 17-106cm, and participants in the Intestinal Rehabilitation Program. Ten healthy, age approximate controls were identified and parents were consented for study. Peripheral blood samples from the experimental and control groups underwent staining for cell surface markers of B cell lineage, maturity, activation, and tissue homing. Cells then underwent flow cytometry analysis. SBS and control groups were compared, with nonparametric tests performed for statistical significance, alpha was set <0.002.

Results: Analysis revealed several abnormalities among the SBS group, a few of which are listed here. Mature IgA+ IgD- B cell lineages were significantly decreased: control 4.86%(2.76-15.3) vs. SBS: 1.67%(0.2-13.6). Class switched B-cell populations were reduced as well: control 17.15%(10.5-26.2) vs. SBS 10.5%(0.18-24.6). Gut homing cells typical of an immature immune system were increased in SBS. CCR9+ IgA- IgD+ cells were increased: control 0.23%(0.074-0.67) vs. SBS 2.48%(0.34-7.77).

Conclusion: This study is the first to determine that pediatric SBS patients have an abnormal B-cell profile. These findings show that SBS is associated with deficient B-cell development. These alterations in the B-cell profile could account for the clinical differences observed between SBS and unaffected children.