Abrogation of surgery-induced IL-6 hypersecretion by presurgical immunotherapy with IL-2 and its importance in the prevention of postoperative complications

Because of its immunosuppressive effect, surgery-induced immunosuppression may depend at least in part on the postoperative hypersecretion of IL-6, which is also responsible for surgical complications. Most of the immunosuppressive events induced by surgery, including lymphocytopenia, NK and T lymphocyte decline, and dendritic cell deficiency have been proven to be abrogated by a preoperative injection of IL-2 for few days. However, the cytokine mechanisms responsible for IL-2-induced abrogation of surgery-related immunosuppression need to be better investigated and understood. This study was performed to analyze the influence of IL-2 presurgical immunotherapy on IL-6 secretion in the postoperative period. The study was performed in 12 operable colorectal cancer patients, who were preoperatively pretreated with IL-2 (12 million lU/day subcutaneously for 3 consecutive days before surgery). The control group consisted of 21 age-and disease-matched colorectal cancer patients who underwent surgery without a preoperative immunotherapy with IL-2. Serum levels of IL-6 were measured by an enzyme immunoassay before surgery, and at days 3 and 7 of the postoperative period. A significant increase in mean serum levels of IL-6 occurred in the postoperative period only in the control patients, whereas in the IL-2 pretreated group no significant difference was seen between presurgical and postoperative IL-6 mean concentrations. The difference between controls and IL-2 group was particularly evident for patients with abnormally elevated presurgical values of IL-6. This study, by showing that a presurgical injection of IL-2 may prevent surgery-induced IL-6 enhanced secretion, would suggest that the previously described neutralization of surgery-induced immunosuppression by IL-2 preoperative immunotherapy may depend at least in part on the inhibition of postoperative production of IL-6, whose immunosuppressive effects have been well demonstrated at least on anticancer immunity.     

Changes in circulating dendritic cells and IL-12 in relation to the angiogenic factor VEGF during IL-2 immunotherapy of metastatic renal cell cancer

Angiogenesis and immunosuppression are the main biological mechanisms responsible for cancer progression. Moreover, recent observations suggesting a negative influence of angiogenesis on anticancer immunity have shown that some angiogenic factors, such as VEGF, may induce immunosuppression. In addition, the evidence of abnormally high blood levels of VEGF has been proven to be associated with resistance to IL-2 immunotherapy. The present study was performed to establish a possible relation ship between the efficacy of IL-2 cancer immunotherapy and changes in circulating levels of VEGF, IL-12, mature and immature dendritic cells (DC). The study included 25 metastatic renal cell cancer patients who underwent subcutaneous low-dose IL-2 immunotherapy (6 MIU/day for 6 days/week for 4 weeks). Immature and mature DCs were identified as CD123+ and CD11c+ cells, respectively. The clinical response consisted of partial response (PR) in five, stable disease (SD) in 11 and progressive disease (PD) in the remaining nine patients. The mean IL-12 levels observed during IL-2 immunotherapy were significantly higher in patients with PR or SD than in those with PD, whereas the mean VEGF concentrations were significantly higher in patients who had PD than in those with PR or SD. Finally, a significant increase in the mean number of circulating mature DCs occurred only in patients with PR or SD, whereas no significant change was seen in patients with PD. By contrast, no significant change was observed in the mean number of immature DCs. This study shows that the efficacy of IL-2 immunotherapy is associated with a significant increase in circulating mature DCs and IL-12, without any concomitant increase in VEGF concentrations. Further studies will be required to better define the relationship between activation of anticancer immunity and control of angiogenesis-related mechanisms.     

Circulating immature and mature dendritic cells in relation to lymphocyte subsets in patients with gastrointestinal tract cancer

Cancer-related deficiency in circulating dendritic cells (DC), whose important anticancer role is well established, has been proven to be associated with lymphocytopenia. This study was performed to evaluate which lymphocyte subset is most markedly related to the failure of the DC system. The study included 30 patients with gastrointestinal tract cancer, 10 of whom had distant organ metastases. Immature and mature DCs were measured by FACS and monoclonal antibodies against CD123 and CD11c antigens, respectively. Low levels of immature and mature DCs were observed in 63% and 43% of patients, respectively. Patients with low levels of circulating mature DCs had significantly lower values of T lymphocytes, T helper lymphocytes and NK cells than those with normal mature DC levels. In contrast, no significant difference was seen between patients with normal or abnormally low values of immature DCs. Conversely, patients with a decreased number of T lymphocytes, T helper lymphocytes and NK cells showed significantly lower values of circulating mature DCs than those with lymphocyte subsets within the normal range, whereas no difference was seen in immature DC amounts. This study suggests that only mature DC deficiency may be associated with important lymphocyte subset alterations in cancer patients, whereas deficiency in immature DCs does not seem to be related to other immune cell disorders.     

Transduction of human dendritic cells with a recombinant modified vaccinia Ankara virus encoding MUC1 and IL-2

The epithelial mucin MUC1 is considered an opportune target antigen for cancer immunotherapy, as it is over-expressed and exhibits aberrant glycosylation in malignant cells. Because dendritic cells (DC) are powerful initiators of immune responses, efforts have focused on tumor antigen-bearing DC as potent cancer vaccines. In this study we have characterized the transduction of monocyte-derived DC with a highly attenuated vaccinia virus vector [modified vaccinia Ankara (MVA)] encoding human MUC1 and the immunostimulatory cytokine IL-2. Analysis of transduced DC cultures generated from a number of donors revealed MUC1 expression in the range of 27-54% of the cells and a co-regulated secretion of bioactive IL-2. As shown by FACS analysis with MUCI-specific antibodies, the MVA-MUC1/IL-2-transduced DC predominantly expressed the fully processed glycoform of MUC1, typical of that displayed by normal epithelia. Over a 3-day period after transduction, transgene expression declined concurrent with an increase in MVA-induced cytopathic effects. The transduced DC stimulated allogeneic lymphocyte proliferation, indicating that DC immunostimulatory function is not impaired by vector transduction. In the presence of IL-2, MVA-transduced DC were able to enhance autologous lymphocyte proliferation. Also, vector expression was analyzed in DC cultures treated with TNF-alpha, a known DC maturation factor. As indicated by the up-regulation of several DC maturation markers, neither virus infection nor transgene expression influenced the maturation capacity of the cells. The MVA-MUC1/IL-2 vector effectively transduced both immature and TNF-alpha-matured DC. Overall, our results are encouraging for the clinical application of MVA-MUC1/IL-2-transduced DC.     

Abnormally enhanced blood concentrations of vascular endothelial growth factor (VEGF) in metastatic cancer patients and their relation to circulating dendritic cells, IL-12 and endothelin-1

Elevated VEGF blood concentrations have been proven to be associated with poor prognosis in human neoplasms. This finding is generally explained as a consequence of the potential angiogenic properties of VEGF itself. However, preliminary experimental studies suggest that VEGF, in addition to its angiogenic activity, may also play an immunosuppressant role by inhibiting dendritic cell (DC) maturation. The present study was performed to analyze blood levels of VEGF in cancer patients in relation to those of another potentially angiogenic tumor growth factor, endothelin-1 (ET-1), and to the absolute number of circulating immature and mature DC, and serum levels of the best known antitumor cytokine, IL-12. The study was performed in 100 healthy controls and in 80 solid tumor patients (colorectal cancer: 24; gastric cancer: 17; cancer of pancreas: 4; lung cancer: 13; breast cancer: 11; renal cell cancer: 6; gynecologic tumors: 5), 48 of whom showed distant organ metastases. In each patient, we have evaluated serum concentrations of VEGF-165, total VEGF, ET-1, IL-12 and the circulating number of immature (CD123+) and mature (CD11c+) DC. Mean serum levels of VEGF-165 were significantly higher in metastatic patients than in controls or in non-metastatic patients, whereas the total amounts of VEGF were not significantly higher. Moreover, it has been observed that patients with abnormally elevated blood concentrations of VEGF-165 showed significantly lower mean values of immature DC, mature DC and IL-12 and significantly higher mean levels of ET-1 than those with normal concentrations. This study, by confirming that advanced neoplastic disease may be associated with increased endogenous secretion of VEGF, seems to suggest that the association between high blood levels of VEGF and poor prognosis in cancer does not depend only on VEGF-induced stimulation of the neovascularization, but also on VEGF-related immunosuppression.     

Signaling lymphocytic activation molecule is expressed on mature CD83+ dendritic cells and is up-regulated by IL-1 beta

Signaling lymphocyte activation molecule (SLAM), a 70-kDa costimulatory molecule that mediates CD28-independent proliferation of T cells and IFN-gamma production, has been identified on human T cells, immature thymocytes, and a subset of B cells. We have found that SLAM is expressed on mature but not immature dendritic cells (DC). However, the SLAM-associated protein, is missing in DC. SLAM surface expression is strongly up-regulated by IL-1beta. Addition of IL-1beta to the DC maturation mixture also increases the stimulatory properties of DC. These findings provide a new marker for DC maturation and help to explain two areas of DC biology. First, SLAM is a receptor for the measles virus, previously shown to infect DC. Second, SLAM could possibly contribute to the enhanced immunostimulatory functions of DC that are observed following the addition of IL-1.     

Immature and Maturation-Resistant Human Dendritic Cells Generated from Bone Marrow Require Two Stimulations to Induce T Cell Anergy In Vitro

Immature dendritic cells (DC) represent potential clinical tools for tolerogenic cellular immunotherapy in both transplantation and autoimmunity. A major drawback in vivo is their potential to mature during infections or inflammation, which would convert their tolerogenicity into immunogenicity. The generation of immature DC from human bone marrow (BM) by low doses of GM-CSF (lowGM) in the absence of IL-4 under GMP conditions create DC resistant to maturation, detected by surface marker expression and primary stimulation by allogeneic T cells. This resistence could not be observed for BM-derived DC generated with high doses of GM-CSF plus IL-4 (highGM/4), although both DC types induced primary allogeneic T cell anergy in vitro. The estabishment of the anergic state requires two subsequent stimulations by immature DC. Anergy induction was more profound with lowGM-DC due to their maturation resistance. Together, we show the generation of immature, maturation-resistant lowGM-DC for potential clinical use in transplant rejection and propose a two-step-model of T cell anergy induction by immature DC.     

Polyriboinosinic polyribocytidylic acid (poly(I:C)) induces stable maturation of functionally active human dendritic cells.

For vaccination strategies and adoptive immunotherapy purposes, immature dendritic cells (DC) can be generated from adherent monocytes using GM-CSF and IL-4. Presently, the only clinically applicable method to induce stable maturation of DC is the use of supernatants of activated monocytes (monocyte-conditioned medium (MCM)). MCM contains an undefined mixture of cytokines and is difficult to standardize. Here we report that stable maturation of DC can be simply induced by the addition of polyriboinosinic polyribocytidylic acid (poly(I:C)), a synthetic dsRNA clinically applied as an immunomodulator. Poly(I:C)-treated DC show a mature phenotype with high expression levels of HLA-DR, CD86, and the DC maturation marker CD83. This mature phenotype is retained for 48 h after cytokine withdrawal. In contrast to untreated DC, poly(I:C)-treated DC down-regulate pinocytosis, produce high levels of IL-12 and low levels of IL-10, induce strong T cell proliferation in a primary allo MLR, and effectively present peptide Ags to HLA class I-restricted CTL. In conclusion, we present a simple methodology for the preparation of clinically applicable mature DC.     

Dendritic cells: limited potential in immunotherapy

Dendritic cells (DC) represent the most potent antigen-presenting cells (APC) of the immune system for their unique capability of presenting antigen to T-cells. Their use as cellular vaccines after charging with antigen ex vivo has been shown to induce protective and therapeutic anti-tumor immunity with regression of tumor manifestations in animal models of experimental cancer therapy. Human monocyte-derived DC (MoDC) generated in vitro in the presence of GM-CSF and IL-4 are regarded equivalent to immature DC. They can be induced to mature under various experimental conditions. MoDC, in their immature as well as mature state have been widely used for experimental as well as for clinical purposes. However, unequivocal proof for the clinical efficiency of MoDC-based anti-tumor vaccinations is still missing. There is now increasing experimental evidence demonstrating that MoDC may be hampered in their ability to migrate in response to inflammatory as well as homeostatic chemataxins. We therefore suggest that MoDC may not represent the equivalent of migratory DC in vivo limiting their use as magic bullets in tumor immunotherapy.     

Final maturation of dendritic cells is associated with impaired responsiveness to IFN-gamma and to bacterial IL-12 inducers: decreased ability of mature dendritic cells to produce IL-12 during the interaction with Th cells

Activation of immature CD83- dendritic cells (DC) in peripheral tissues induces their maturation and migration to lymph nodes. Activated DC become potent stimulators of Th cells and efficient inducers of Th1- and Th2-type cytokine production. This study analyzes the ability of human monocyte-derived CD1a+ DC at different stages of IL-1 beta and TNF-alpha-induced maturation to produce the major Th1-driving factor IL-12. DC at the early stages of maturation (2 and 4 h) produced elevated amounts of IL-12 p70 during interaction with CD40 ligand-bearing Th cells or, after stimulation with the T cell-replacing factors, soluble CD40 ligand and IFN-gamma. The ability to produce IL-12 was strongly down-regulated at later time points, 12 h after the induction of DC maturation, and in fully mature CD83+ cells, at 48 h. In contrast, the ability of mature DC to produce IL-6 was preserved or even enhanced, indicating their intact responsiveness to CD40 triggering. A reduced IL-12-producing capacity of mature DC resulted mainly from their impaired responsiveness to IFN-gamma, a cofactor in CD40-induced IL-12 p70 production. This correlated with reduced expression of IFN-gamma R (CD119) by mature DC. In addition, while immature DC produced IL-12 and IL-6 after stimulation with LPS or Staphylococcus aureus Cowan I strain, mature DC became unresponsive to these bacterial stimuli. Together with the previously described ability of IL-10 and PGE2 to stably down-regulate the ability to produce IL-12 in maturing, but not in fully mature, DC, the current data indicate a general resistance of mature DC to IL-12-modulating factors.     

TNF-alpha-treated DC exacerbates disease in a murine tumor metastasis model

Due to the pivotal role that dendritic cells (DC) play in eliciting functional anti-tumor T cell responses, immunotherapeutic approaches utilizing DC-based vaccines have readily been exploited. It has been argued that, in the setting of immunotherapy, mature DC will be more efficient at T cell priming and, therefore, required for effective vaccination. As TNF-alpha is commonly used as a DC maturation factor, we have examined the efficacy of treatment with DC matured with TNF-alpha (DC-TNF) in a murine model of melanoma. We have now shown that treatment with DC-TNF leads to an increase in the number of lung metastases as compared to mice treated with immature DC. No differences in the number of CD4⁺CD25⁺ T-regulatory cells were measured in the lungs of DC-TNF-treated mice. On examination of the infiltrating lymphocytes, an enhanced secretion of IL-10 and a higher percentage of CD4⁺IL-10⁺ T cells were measured in the lungs of DC-TNF-treated mice. However, treatment with DC-TNF did not enhance the number of melanoma lesions in the lungs of IL-10 knockout mice or in mice depleted of CD4⁺ T cells. Together, these studies indicate that treatment of melanoma-bearing mice with DC treated with TNF-alpha can induce IL-10 production by resident cells at the tumor site, leading to immune tolerance and exacerbation of disease.     

Platelets, after exposure to a high shear stress, induce IL-10-producing, mature dendritic cells in vitro

There is evidence for immune system involvement in atherogenesis. In the present study the effect of platelets on dendritic cells (DC), an important immunologic regulator, was examined in vitro. Platelet-rich plasma, after exposure to shear stress, was added to human monocyte-derived immature DC, which were then examined for surface Ag expression, allogeneic T lymphocyte stimulatory activity, and cytokine production. After exposure, the number of anti-CD40 ligand (anti-CD40L) and anti-P-selectin IgG molecules bound per platelet was increased. These activated platelets induced DC maturation, as revealed by significant up-regulation of CD83, CD80, and CD86 Ags. The addition of platelets in the presence of IFN-gamma plus LPS significantly enhanced IL-10 production from immature DC. After platelet addition, mature DC provoked a significant proliferation of allogeneic naive T lymphocytes. These activated T cells showed lower IFN-gamma production than those stimulated by LPS- and IFN-gamma-treated DC. CD40L on the platelet surface was not involved in maturation of DC, as mAb to CD40L failed to block maturation. The effect of platelets was observed even if platelets and DC were separated using large pore-sized membranes or when platelets were depleted from plasma by centrifugation. Furthermore, it was abrogated after the depletion of protein fraction. Thus, soluble protein factors excreted from activated platelets contribute to IL-10-producing DC maturation.     

Dynamic change in plasma leptin level during the perioperative period

OBJECTIVE: To examine the association of plasma leptin level with insulin, which is known as a metabolic regulator of leptin, and various stress-related factors during the perioperative period. METHODS: Thirty-one patients undergoing gastrectomy were enrolled and blood samples were obtained preoperatively, intraoperatively, immediately after operation, and on the first and second postoperative days. RESULTS: The plasma leptin level showed a triphasic response. Immediately after operation, the leptin level was the lowest, while the serum cortisol and interleukin-6 (IL-6) levels had their peak (PHASE 1). On the first postoperative day, the leptin level had its peak with the serum cortisol and IL-6 level remaining elevated (PHASE 2). On the second postoperative day, while the serum cortisol and IL-6 levels still remained elevated, the plasma leptin level fell to the preoperative value (PHASE 3). The plasma leptin level correlated well with the insulin level at all time points during the study period. CONCLUSION: Our results suggest a possible role of leptin in harmonizing neuroendocrine and immune responses with energy balance.     

Standardized generation of fully mature p70 IL-12 secreting monocyte-derived dendritic cells for clinical use

Dendritic cells (DC) have been shown to be efficient antigen-presenting cells (APC) and, as such, could be considered ideal candidates for cancer immunotherapy. Immature DC (iDC) efficiently capture surrounding antigens; however, only mature DC (mDC) prime naive T lymphocytes. Clinical trials using DC-based tumor vaccines have achieved encouraging, but limited, success, possibly due to the use of immature or incompletely mature DC. Thus, it was apparent that a method capable of generating large numbers of fully functional iDC, their pulsing with desired form of tumor antigens and the subsequent complete and reproducible maturation of iDC is needed. Therefore, we compared two different methods of producing large numbers of iDC. Both protocols yielded comparable numbers of cells with an iDC phenotype with phagocytic function. We next determined which of the clinically applicable activators could induce the complete and reproducible maturation of DC, in order to define the most suitable combination for future clinical trials. Only a combination of TNFalpha + Poly (I:C), or a previously described cytokine cocktail of TNFalpha + IL-1beta + IL-6 + prostaglandin E2, induced the complete activation of the whole DC population, as assessed by the cell surface expression of CD83 and costimulatory molecules. The matured DC were functionally superior to iDC in their ability to stimulate the proliferation of allogeneic lymphocytes and autologous keyhole limpet hemocyanin (KLH)-specific T lymphocytes. Furthermore, only the combination of TNFalpha + Poly (L:C) activated DC to produce large amounts of biologically active p70 IL-12. Thus DC maturation by TNFalpha + Poly (I:C) could efficiently bias T cell response towards Th1 response. Implementation of our results into clinical protocols used for DC generation could be beneficial for future immunotherapy trials.     

Development of a standardized protocol for reproducible generation of matured monocyte-derived dendritic cells suitable for clinical application

There is increasing interest in the generation of dendritic cells (DC) for cancer immunotherapy. In order to utilize DC in clinical trials it is necessary to have standardized, reproducible and easy to use protocols. We describe here the process development for the generation of DC as the result of investigation of culture conditions as well as consumption rates of medium and cytokines. Our studies demonstrate that highly viable DC (93 ± 2%) can be produced from CD14⁺ enriched monocytes via immunomagnetic beads in a high yield (31 ± 6%) with X-VIVO 15, 400 U ml⁻¹ GM-CSF and 2000 U ml⁻¹ IL-4 without serum and feeding. For the maturation of DC different cocktails (TNF-α, IL-1β, IL-6, PGE₂ and TNF-α, PGE₂) were compared. In both cases cells expressed typical surface molecules of mature DC and induced high proliferative responses in mixed lymphocyte reactions which led to IFN-γ producing T-lymphocytes. The data suggest that the use of this optimized, easy to use protocol results in highly mature DC. This revised version was published online in July 2006 with corrections to the Cover Date.     

Butyrate inhibits functional differentiation of human monocyte-derived dendritic cells

Dendritic cells (DCs) play a key role in immune function through antigen presentation by MHC and CD1, as well as cytokine production that shapes the immune response. Here we report that butyrate, a histone deacetylase inhibitor, inhibits the functional differentiation of human monocyte-derived DCs. Mature DCs were generated from monocytes in the presence of granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), followed by 2 day LPS stimulation. Butyrate treatment throughout the culture period inhibited the expression of CD1 molecules, but not on CD83, CD86, and MHC molecules. The suppression was exerted at protein and mRNA levels. Butyrate-treated immature DCs also showed decreased expression of CD1 molecules. Moreover the butyrate-treated immature DCs showed lower production of IL-12 p40 and IL-6 in response to lipopolysaccharides and induced less Th1 cells in allogenic mixed lymphocyte reactions. Our results imply that histone acetylation is involved in regulating immune responses through regulating functional differentiation of DC. Thus HDAC may be one of the targets for controlling the immune response.     

Generation of tumor cell lysate-loaded dendritic cells preprogrammed for IL-12 production and augmented T cell response

Dendritic cells (DC) loaded with tumor associated antigens (TAA) are often used for the vaccination of cancer patients; however methodologies for the vaccine preparation have not yet been standardized. The purpose of this work was to optimize the ex-vivo production of functional TAA-loaded DC that would produce interleukin-2 (IL-12) and enhance the T cell response. We generated ex-vivo DC from human monocytes with granulocyte macrophage-colony stimulating factor (GM-CSF) and IL-4, and whole necrotic tumor cells (cell lysates) of cancer cell lines were used as model TAA. DC were loaded with lysates without or with additional tumor necrosis factor-alpha (TNF-alpha), or cytokine combination treatments and tested for functional ability in vitro. Tumor cell lysates alone did not fully mature DC either phenotypically or functionally. After antigen uptake additional maturation signals were necessary. TNF-alpha matured DC phenotypically, but additional interferon-gamma (IFN-gamma) treatment was necessary to achieve functional maturation, the production of significant amounts of IL-12. Since IL-12 production by DC increased during the first 24 h of maturation and declined by 48 h, proper timing of the ex-vivo DC treatment was crucial for the generation of functionally mature antigen-loaded DC. Our results suggest that after allowing 4 h of tumor lysate uptake by immature DC, further treatment with TNF-alpha and IFN-gamma for 24 h provides the optimal conditions to obtain functional TAA-loaded DC. These TAA-loaded cytokine pretreated DC then prime na?ve T cells, and enhance both T helper 1 (Th1), Th2 and cytotoxic T lymphocyte (CTL) responses, that are necessary to achieve an effective, specific anti-tumor response.     

Circulating dendritic cells in early and advanced cancer patients: diminished percent in the metastatic disease

Despite the well demonstrated fundamental role of dendritic cells (DC) in generating antitumor immunity in experimental conditions, to date there are only few preliminary studies which investigate the percent of DC in the peripheral blood of cancer patients. Several cell surface markers have now been described which are specific to cultured DC, however their expression in vivo is still controversial. Recently, however, two DC subsets, consisting of immature and mature DC, have been shown to be present in peripheral blood, which can be recognized as CD123+ and CD11c+ cells, respectively. On this basis, we decided to investigate the presence of both mature and immature DC in the peripheral blood of early or advanced cancer patients. The study included 40 solid tumor patients, 18 of whom had a locally limited disease, while the other 22 showed distant organ metastases. CD123+ and CD11c+ cells were detected by FACS using monoclonal antibodies, and expressed as the percent of total leukocytes. The control group consisted of 50 healthy subjects. The mean percent of both CD123+ and CD11c+ cells was significantly lower in cancer patients than in controls. Moreover, the mean percent of both DC subsets was significantly lower in metastatic patients than in the non-metastatic ones. This study, demonstrating significantly lower percents of both immature and mature DC in the peripheral blood of cancer patients, particularly in those with distant organ metastases, suggests that DC deficiency may play a role in inducing cancer-related immunosuppression. Therefore, the demonstration of a diminished percent of DC in peripheral blood may represent a new interesting biological marker predicting a poor prognosis in human neoplasms, as with lymphocytopenia, the unfavourable prognostic significance of which has been well demonstrated.     

Ghrelin as an acute-phase reactant during postoperative stress response.

Ghrelin is a growth hormone-releasing peptide, discovered in 1999 by Kojima et al. Its potential role in inflammation and stress response is not yet clear. The purpose of this study was to characterize perioperative levels of circulating ghrelin in relation to different surgical procedures. The authors compared plasma ghrelin changes with cortisol, cytokines, and acute-phase proteins. The prospective study was performed on 22 patients with resection for colon cancer (group 1). Group 2, functioning as a comparative group, consisted of 22 patients with elective laparotomic cholecystectomy. Plasma concentrations of ghrelin, cortisol, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta, IL-6, IL-8, soluble IL-2 receptor, C reactive protein, and alpha1-antitrypsin were estimated repeatedly during a 72-hour postoperative period. Data revealed significant elevation of plasma ghrelin 24 hours after resection of coli (median 508.0 ng/l, interquartile range 398.2-633.7 ng/l) in relation to both preoperative levels (317.6 ng/l, 253.4-355.1 ng/l, p<0.01) and group 2 maximal postoperative levels (386.2 ng/l, 324-432 ng/l, p<0.05). Ghrelin levels returned to initial status 36-48 hours after surgery with subsequent decline to subnormal levels. The regression coefficient was the highest for ghrelin and TNF-alpha 24 hours after laparotomy (r=0.64, p<0.05) and for ghrelin and IL-6 24 hours after surgery (r=0.56, p<0.05). Maximal postoperative levels of all tested parameters except for cortisol and IL-1beta differed significantly between both patient groups at p<0.05. After large abdominal surgery, ghrelin shows itself as an acute-phase reactant. The significant correlation between ghrelin and inflammatory cytokines supposes their regulatory role in this period. Our comparison of more- and less-invasive surgical procedures with similar nutritional restrictions argues for a dominant role of inflammatory factors in postoperative ghrelin elevation.