SPP1 and intestinal obstruction: To determine if OPN plays a role in the impairment of T and B lymphopoiesis and maintenance in bowel obstruction, we quantitated total lymphocyte numbers and analyzed T and B cells by flow cytometry in the spleen, thymus, and bone marrow (Figures 8A–C) in wild-type (OPN+/+) and OPN gene knockout (OPN−/−) mice.