The Trends Of Phenotype-and Function-related Molecules On B Cells In Mice With The Early Stage Of Sepsis

ObjectiveThis study was to investigate the changes of B cells subpopulations, costimulatorymolecules expression and function of secreting cytokines in peripheral blood, spleen andabdominal cavity in mice with sepsis. The aim of this study was to explore whether Bcells show abnormal function in sepsis.Measurements1. Experimental sepsis was induced by cecal ligation and puncture. A total of24C57BL/6mice were divided into sham group (n=6) and CLP group (n=18) including6hgroup,24h group, and48h group (n=6for each group). The percentage of CD19+CD5+B cells, CD19+CD21+B cells, CD19+CD23+B cells and CD19+CD27+B cells aredetected by flow cytometry in blood, spleen and abdominal cavity. The percentage ofCD40, CD69, CD80and CD86positive cells as well as the average fluorescent of mIgMand mIgD were also assessed in the different groups.2. Experimental sepsis was induced by cecal ligation and puncture. A total of24C57BL/6mice were divided into sham group (n=6) and CLP group (n=18) including6hgroup,24h group, and48h group (n=6for each group). The blood and peritoneal lavagefluid were harvested6h,24h and48h after surgery to determinate the level of GM-CSF,IL-10and IgM by ELISA.Results1.In the blood, CD19+CD5+B cells were not changed significantly at the different timeafter CLP surgery. CD19+CD21+B cells and CD19+CD23+B cells were decreased after CLPuntil48h when a minimum value achieved (p<0.01). CD19+CD27+B cells were elevated at6h after CLP, but reduced at48h (p<0.05). As the functional markers: CD40wassignificantly upregulated after surgery, peaked at6h (p<0.05). CD69expression was onlyelevated at24h after surgery (p<0.01). The level of CD86rose at6h, dropped down at24hand back to normal at48h (p<0.01). The expression of mIgM on B cells was elevated at6hafter surgery, decreased at24h, and then back to normal level at48h (p<0.01). 2. In the spleen, there was no difference in CD19+CD5+B cells and CD19+CD21+Bcells among different groups. The percentage of CD19+CD23+B significantly decreased at24h and48h after CLP operation (p<0.01). CD19+CD27+B cells increased48h after surgery(p<0.01). As for the functional markers: the expression of CD40and mIgM were notchanged among the groups. The level of CD69expression increased at6h (p<0.01), peakedat24h. CD80was upregulated at24h after CLP, peaked at48h. The level of CD86waselevated and peaked at24h, when at48h, it slightly decreased but still higher than othergroups(p<0.01). The level of mIgD was incresed at48h after surgery (p<0.01).3. In peritoneal cavity, the number of CD19+CD5+B1cells decreased at6h and24hafter CLP operation (p<0.05), and back to normal level at48h (p<0.01). As for functionalmarkers: CD40was not change among the groups. CD69kept at high level after CLPoperation (p<0.01). The level of CD80rose at24h after operation (p<0.01). CD86showed asignificant higher level at6h and24h, while remarkably decreased at48h (p<0.01). The levelof mIgM and mIgD increased at6h after CLP operation,were minimumed at24h and48hrespectively(p<0.01).4.The level of IgM in serum was decreased at48h after CLP operation(p<0.05). Inperitoneal lavage fluid, the level of IgM increased at6h and peaked at48h. The levels ofGM-CSF and IL-10were elevated at6h, peaked at24h and back to normal level at48h aftersurgery (p<0.01).ConclusionCD19+CD23+B cells may be the major type of defected B cells during sepsis,suggesting that B cells involved in the acquired immune system is impacted by sepsis.Thepercentage of CD19+CD5+B cells decrease in the abdominal cavity, at the early stage ofsepsis, but they seem to be capable of renewing themselves by self-expansion.B lymphocytes in different sites are activiated during sepsis. The co-stimulatorymolecules CD40, CD80and CD86are all elevated early after sepsis. But they decrease later,even at a lower level than the normal level. It again suggests that the ability in acquiredimmune response of B cells is impaired during sepsis.