The predominance of a naive T helper cell subset in the immune response of experimental acute pancreatitis

Introduction: In necrotizing acute pancreatitis (NAP), systemic inflammatory response syndrome (SIRS) and the compensatory anti-inflammatory response syndrome (CARS) decide overall outcome and mortality. In patients, low lymphocyte counts were found, but T-helper cells seemed to conversely increase. Our aim was to further categorize T-helper cells within the context of NAP induced SIRS and CARS.

Methods: NAP was induced by injection of sodium-taurocholate into the common bile duct of male BALB/c mice; sham treated animals received saline infusion. The animals were sacrificed at 6, 12, 24 and 48 h later. Lymphocytes from blood, liver and spleen were isolated and examined by flow cytometry. Staining was performed for CD4, CD8, CD19, CD45RB, CD25, CD69, and CD152. CD4⁺ cells were sorted for their CD45RB expression and sought for gene regulation associated to T_H1/T_H2 cells by quantitative RT-PCR.

Results: In NAP, CD4⁺ was solely increased in all compartments. CD8⁺ remained without substantial alterations. CD45RB showed significant expression in RB^high in T-helper cells, confirmed by the CD45RB^high/low ratio (Liver, 24 h: NAP 2.2, SHAM 0.6; p < 0.001). CD45RB^high and ^-low cells were not associated to patterns of T_H1/T_H2 expression. In NAP, CCR4 expression was significantly decreased within RB^high cells (fold change: 0.04, p < 0.05), while TLR6 showed significant overexpression (fold change: 2.36, p < 0.05).

Conclusion: T-helper cells increase in NAP, leaning towards CD45RB^high expression. They resemble naive T-cells, in which NAP leads to expression profiles associated with an innate immune response. This suggests new findings in immunological pathomechanisms of NAP.