The role of resident immune cells in organogenesis has not been extensively studied in pancreas. We hypothesized that during the critical stage of ß-cell remodeling during the newborn period, immune cell populations would also change. Using flow cytometry and immunohistochemistry, we identified immune cell populations in the endocrine (islets) and exocrine portion of the pancreas at postnatal day 1, 7 and 14. When corrected for the expected increase in pancreatic weight, immune cell populations increase in the exocrine pancreas in males and females from P1 to P7 but not further at P14. Interestingly, in islets the number of immune cells further increases in males from P7 to P14. Macrophages, T cells, B cells, granulocytes and NK cells are present in islets and exocrine pancreas. Macrophages are the dominant population in islets (M: 47%, F: 47%) and exocrine (M:30%, F: 34%) pancreas. In islets, M2 macrophages are favored at P1. M1 macrophages dramatically decrease with age. In exocrine pancreas, M1 macrophages are initially favored, but with age the M2 population increases. T cells are also present in islets (M:6%, F:6%) and exocrine (M:8%, F: 6%) pancreas. Cd3+ Cd4- Cd8- is the dominant T cell population at P1 but decreases with age replaced by Cd3+ Cd4+ Cd8- cells. In islets from male, but not females, the number of T cells, specifically Cd4+ T cells, increases with age. B cells (Cd45Ra+) are present in islets (M:20%, F:19%) and exocrine (M:20%, F:25%) pancreas and numbers do not change with age. Neutrophils (HIS48hi Cd68) are also present in islets (M:6%, F:6%) and exocrine (M:13%, F: 10%) pancreas. NK cells are a minor cell population present at about 1% of total immune cells in male and female pancreas at P1. Interestingly, NK cells increase with age in females in islets and exocrine pancreas. These data demonstrate significant sex specific changes in the pancreas during the critical period of postnatal pancreas development suggesting a role for immune cells in normal postnatal development and function in the endocrine and exocrine pancreas.
T. Golden: None. G. Worthen: None. R.A. Simmons: None.
National Institutes of Health