Clinical observation of immunity in patients with secondary infection from severe acute pancreatitis

To observe immune system changes in patients with secondary infection from severe acute pancreatitis (SAP). Seventy-nine patients were recruited. The percentages of CD4+, CD8+, natural killer (NK), HLA-DR+ cells and B lymphocytes, and the CD4+/CD8+ ratio, were determined. In addition, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), interleukin-10 (IL-10), and interleukin-4 (IL-4) serum levels were determined on days 1, 7, 14, and 28. Fifteen patients had a secondary infection. The immune response of the infected group was quite different from the non-infected group, with a higher percentage of CD4+ and HLA-DR+ cells on days 1, 7, 14 and 28, a higher percentage of CD8+ and NK cells on days 14 and 28, a reduced CD4+/CD8+ ratio, and a reduction in B lymphocytes. The cytokine levels in the infected group were different from the non-infected group, with a rise in TNF-alpha and IL-6 through the first 2 weeks, but dropping at 1 month. IL-10 and IL-4 increased initially, but then dropped over the next 3 weeks. An early excessive immune response followed by a subsequent immune deficiency is closely related to secondary SAP infection.