Monocyte anergy is present in patients with severe acute pancreatitis and is significantly alleviated by granulocyte-macrophage colony-stimulating factor and interferon-gamma in vitro.

OBJECTIVES

Severe acute pancreatitis (AP) is frequently associated with immune suppression, which increases the risk of infections, organ failure, and death. Our aims were to measure monocyte function (ie, HLA-DR expression and tumor necrosis factor-alpha [TNF-alpha] production as markers of immune suppression) in patients with severe AP and to determine whether treatment of blood samples with granulocyte-macrophage colony-stimulating factor (GM-CSF) and/or interferon-gamma (IFN-gamma) corrected the functional defects of monocytes in vitro.

METHODS

The study consisted of 28 patients with severe AP who were treated at intensive care unit and in whom the proportion of HLA-DR-positive monocytes in the circulation was less than 70%, and 28 matched control subjects who were selected from healthy laboratory personnel. HLA-DR density was determined by whole blood flow cytometry. Monocyte TNF-alpha production in response to bacterial lipopolysaccharides (LPSs) was studied in a whole blood assay. Aliquots of blood were supplemented with IFN-gamma (all 28 patients), GM-CSF (the last 24 patients), or both (the last 12 patients).

RESULTS

The median proportion of HLA-DR-positive monocytes was 45% in patients (range, 18%-73%) and was 98% in controls (range, 86%-100%; P < 0.001). TNF-alpha levels in response to LPSs were lower in patients (545 pg/mL; range, 84-1990 pg/mL) than in controls (1415 pg/mL; range, 660-5490 pg/mL; P < 0.001). The proportion of HLA-DR-positive cells correlated positively with TNF-alpha levels (r = 0.56; P < 0.01). Both GM-CSF and IFN-gamma increased HLA-DR expression of monocytes in patients (98%; range, 74%-100% for GM-CSF; 99%; range, 86%-100% for IFN-gamma; both P < 0.001). The combination restored monocyte HLA-DR expression (99%; range, 96%-100%; P = 0.002). Compared with basal levels, GM-CSF increased TNF-alpha production of monocytes both in blood samples from patients (median, 1320 pg/mL; range, 35-8015 pg/mL) and controls (median, 3450 pg/mL; range, 1040-9835 pg/mL; both P < 0.001). IFN-gamma increased TNF-alpha production by monocytes in patients (683 pg/mL; range, 186-2705 pg/mL; P < 0.05) but not in controls (1658 pg/mL; range, 765-4755 pg/mL; P = 0.31). With the combination of GM-CSF and IFN-gamma, the TNF-alpha levels of monocytes in patients (3185 pg/mL; range, 545-8280 pg/mL) and in controls (2800 pg/mL; range, 1080-6860 pg/mL) were comparable.

CONCLUSIONS

The proportion of HLA-DR-positive monocytes correlates with TNF-alpha production, and they both reflect the degree of immune suppression. The low proportion of HLA-DR-positive monocytes in AP can be reversed in vitro by GM-CSF and/or IFN-gamma. The GM-CSF and IFN-gamma treatments also increase LPS-induced TNF-alpha production. By the combination of GM-CSF and IFN-gamma, but not by either agent alone, LPS-induced TNF-alpha production of monocytes was equally high in patients and in controls.