Increased Level of Soluble Interleukin-2 Receptor in Advanced Solid Tumors: A Preliminary Study

Reigniting hope in cancer treatment: the promise and pitfalls of IL-2 and IL-2R targeting strategies

Interleukin-2 (IL-2) and its receptor (IL-2R) are essential in orchestrating immune responses. Their function and expression in the tumor microenvironment make them attractive targets for immunotherapy, leading to the development of IL-2/IL-2R-targeted therapeutic strategies. However, the dynamic interplay between IL-2/IL-2R and various immune cells and their dual roles in promoting immune activation and tolerance presents a complex landscape for clinical exploitation. This review discusses the pivotal roles of IL-2 and IL-2R in tumorigenesis, shedding light on their potential as diagnostic and prognostic markers and their therapeutic manipulation in cancer. It underlines the necessity to balance the anti-tumor activity with regulatory T-cell expansion and evaluates strategies such as dose optimization and selective targeting for enhanced therapeutic effectiveness. The article explores recent advancements in the field, including developing genetically engineered IL-2 variants, combining IL-2/IL-2R-targeted therapies with other cancer treatments, and the potential benefits of a multidimensional approach integrating molecular profiling, immunological analyses, and clinical data. The review concludes that a deeper understanding of IL-2/IL-2R interactions within the tumor microenvironment is crucial for realizing the full potential of IL-2-based therapies, heralding the promise of improved outcomes for cancer patients.

Serum levels of interleukin-2 in cancer patients: Preliminary considerations

In order to investigate the production of interleukin-2 (IL-2) in human neoplasms, we determined IL-2 and soluble IL-2 receptors (sIL-2R) in serum from 18 patients with lymphoma and 28 patients with solid tumors, with (15 cases) or without (13 cases) metastases. As controls, 58 healthy subjects were evaluated. Low levels of IL-2 were not observed in patients with lymphoma or limited solid tumor but abnormally low concentrations of IL-2 were seen in 4/15 metastatic solid tumors, associated with abnormally high values of sIL-2R. This preliminary study confirms in vivo the reduced IL-2 production in metastatic solid neoplasms, previously documented in vitro

Soluble Interleukin-2 Receptors in Patients with Advanced Colorectal Carcinoma

The levels of soluble interleukin-2 receptors (sIL-2R) were measured in the serum of 52 patients with advanced colorectal carcinoma and compared to CEA and CA 19-9 levels. Twenty-five normal, age and sex-matched individuals served as controls. Seventy-five per cent of the patients had increased mean serum levels of sIL-2R (1539 ± 155 U/ml), while normal controls had mean levels of 555 ± 31 U/ml (p < 0.001). The relationship with hepatic or lymph nodal metastases showed no statistically significant difference (p=0.34 and p=0.47, respectively). Serum sIL-2R levels showed a linear correlation with CEA (p < 0.05). Patients with lower pretreatment sIL-2R levels (less than 1.200 U/ml) had a longer survival than patients with higher initial levels (more than 1.200 U/ml) (p=0.0049).

In conclusion, the present work shows that the serum levels of sIL-2R: a) are elevated in patients with advanced colorectal cancer, b) have no relationship with the type of metastases, c) correlate with serum CEA and d) have a prognostic value for survival.

Immunobiology of gestational trophoblastic diseases

Gestational trophoblastic diseases (GTDs) comprise a group of interrelated diseases characterized by development after gestation, widespread metastases, and high curability with chemotherapy. The good prognosis of GTDs is considered partly a result of the host immune response to paternal antigens expressed on trophoblastic cells. In this study, we review current understanding of the immunobiology of GTDs. First of all, we describe the microenvironment between trophoblastic cells and subpopulation of immune cells. Second, immunogenetics, immune microenvironment around abnormal trophoblast, and mechanism of GTDs escaping from maternal immune system surveillance were also discussed. Third, we propose the possible immunotherapy for persistent GTDs, particularly the vaccine designed on human chorionic gonadotrophin, which is generally accepted as a tumor marker for GTDs diagnosis. Due to the low incidence of GTDs and high response to chemotherapy, there have been few literatures about immunobiologic characteristics of GTDs compared with the other gynecologic malignancies, such as ovarian cancer, but the immunologic behavior of GTDs should be explored for further understanding of the etiology of these diseases and to help designing immunotherapeutic strategies for persistent GTDs.

The clinicopathological significance of preoperative serum-soluble interleukin-2 receptor concentrations in operable non-small-cell lung cancer patients

BACKGROUND

Serum-soluble interleukin-2 receptor (IL-2R) concentrations have been found to be elevated in cancer patients. However, the importance of this finding in patients with non-small-cell lung cancer (NSCLC) has not been previously established.

METHODS

Preoperative serum-soluble IL-2R concentrations were determined in 65 consecutive patients with operable NSCLC. The correlation of preoperative serum-soluble IL-2R concentrations with various clinicopathological features of this cancer was evaluated to clarify the clinical significance of this parameter.

RESULTS

Although serum-soluble IL-2R concentrations were not significantly higher in operable NSCLC patients than in normal controls (P = .1180), serum-soluble IL-2R concentrations were significantly higher in patients with stage IIIB or IV disease than in normal controls (P = .0001). The presence of intrapulmonary metastasis was the only clinicopathological feature that was significantly correlated to serum-soluble IL-2R concentration (P = .0004). The sensitivity of serum-soluble IL-2R concentration in identifying the presence of intrapulmonary metastasis was 87.5%; specificity was 75%.

CONCLUSIONS

Elevated preoperative serum-soluble IL-2R concentrations in patients with operable NSCLC reflect the occurrence of intrapulmonary metastasis. Preoperative examination of serum-soluble IL-2R concentrations may be valuable in the detection of the intrapulmonary metastasis preoperatively.

Prognostic significance of soluble interleukin-2 receptor-alpha in adenocarcinoma of the pancreas

Soluble interleukin-2-receptor-alpha (sIL-2Ralpha) serum concentrations were examined in chronic pancreatitis patients, patients with cystadenocarcinoma of the pancreas, patients with adenocarcinoma of the pancreas and healthy blood donors. sIL-2Ralpha serum concentrations in pancreatic cancer patients were significantly higher than those of normal control subjects or chronic pancreatitis patients. In patients with adenocarcinoma of the pancreas no significant differences were found between sIL-2Ralpha and tumor size, grading, resectability and lymph node involvement. In Kaplan-Meier regression analysis patients with adenocarcinoma of the pancreas with low sIL-2Ralpha levels (<500 U/ml) lived significantly shorter than patients with sIL-2Ralpha concentrations above 500 U/ml (P < 0.01), suggesting that determination of sIL-2Ralpha serum concentrations could provide additional important information about prognosis.

Increased serum concentrations of soluble tumor necrosis factor receptor I in noncachectic and cachectic patients with advanced gastric and colorectal cancer

The serum levels of soluble tumor necrosis factor receptor I (sTNF-RI) were measured in 74 noncachectic patients including 42 with gastric cancer and 32 with colorectal cancer, as well as in 39 patients with severe cachexia and 15 healthy volunteers. The sTNF-RI levels increased with the advance of disease, being highest in the cachectic patients. The levels were inversely correlated with the serum concentrations of nutritional parameters such as prealbumin, transferrin, retinol binding protein, and the percentages of CD3(+) cells in the peripheral blood lymphocytes, and positively correlated with the serum concentration of immunosuppressive acidic protein (IAP) and soluble interleukin-2 receptors. These findings suggest that sTNF-RI could be an important prognostic factor to predict the advance of gastric and colorectal cancers and deterioration of the patient's nutritional and immune activity.

Serum Soluble Interleukin-2 Receptor Levels in Patients with Breast Cancer

Preoperative levels of serum soluble interleukin-2 receptor (1L-2R) were examined in 37 patients with breast cancer. We investigated the correlations of serum soluble IL-2R levels with various factors such as stage grouping, lymph node metastasis, distant metastasis, tumor size, histophthological type, estrogen receptor (ER), progesterone receptor (PgR) and CA 15-3. Serum soluble 1L-2R levels were measured with an enzyme-linked immunosorbent assay. Levels of serum soluble 1L-2R in the patients with stage III and IV breast cancer were significantly higher than those in the normal controls, and patients with stage I and II breast cancer. Preoperative levels of serum soluble IL-2R in patients with T3 and T4 were also significantly higher than those in patients with T1 and T2. Serum levels of IL-2R in patients with distant metastasis were also significantly higher than those in patients without distant metastasis. Moreover, serum levels of soluble IL-2R in patients with higher CA 15-3 were significantly higher than those in patients with normal CA 15-3 levels. We conclude that preoperative serum soluble IL-2R levels in patients with breast cancer may be a valuable parameter, especially in evaluating whether they have distant metastasis or not.

Interleukin-10 as a possible mediator of immunosuppressive effect in patients with squamous cell carcinoma of the head and neck

BACKGROUND

Depressed cell-mediated immunity is a frequent event in patients with head and neck cancer and is characterized by impairment of T cell-proliferative responses and natural killer cell and lymphokine-activated killer cell activity. This immunosuppressive effect appears to be mediated by a serum-derived factor. Certain cytokines, including transforming growth factor-beta (TGF-beta) and interleukin (IL)-10 have been shown to induce similar immunosuppressive effects. The present study was designed to examine the putative role of these cytokines in cellular immune suppression induced by patient serum.

METHODS

Serum was collected from multiple patients with newly diagnosed or recurrent squamous cell carcinoma of the head and neck. The serum was heat inactivated for 30 min and frozen in aliquots. Peripheral blood lymphocytes were isolated from normal human blood. Lymphocytes were suspended in RPMI and 15% concentrations of control and patient serum and stimulated with 0.75 mg% phytohemagglutinin. In addition, neutralizing antibodies to TGF-beta and IL-10 were added to lymphocyte cultures. At 24 h, and IL-2 response assay was performed. Finally, the sera were examined for the presence of TGF-beta and IL-10 using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

In seven of seven experiments, incubating cells with a neutralizing antibody to TGF-beta failed to counteract the immune suppression and restore proliferative response to IL-2. Also, an ELISA of these sera failed to demonstrate the presence of TGF-beta. In contrast, four of five experiments performed with neutralizing antibody to IL-10 showed significant restoration of proliferation in the presence of this antibody. Also, ELISA showed elevated IL-10 levels in 65% of the patients' sera in comparison to controls.

CONCLUSION

We conclude that TGF-beta is not responsible for the immunosuppressive effects induced by head and neck patient sera. However, the suppressive effect is reversed by blocking the biologic action of IL-10. Further experiments are needed to define the role of IL-10 in inducing the immunosuppressive effect.

Serum levels of interleukins 2, 6 and 8, soluble interleukin-2 receptor and intercellular adhesion molecule-1 during treatment with interleukin-2 plus interferon-alfa

In the present study we evaluated the haematological and immunological changes in 4 patients with advanced melanoma and 6 patients with advanced renal cell carcinoma treated with subcutaneous interleukin (IL)-2 and interferon (IFN)-alfa-2b. Serum samples taken before and during six weeks' courses of IL-2 plus IFN-alfa were assayed for the presence of IL-2, soluble IL-2-receptor (sIL-2R), soluble intercellular adhesion molecule-1 (sICAM-1), IL-6 and IL-8. In addition, whole blood counts were taken. Eosinophilia occurred in all patients, lymphocytosis in 8 patients. The higher maximum level of IL-2 during treatment seemed to be connected to longer survival: it was a median of 578 pg/ml in the patients with a median survival of 7 months, and 1025 pg/ml in the patients who survived a median of 15 months. Conversely, an increase in sIL-2R was an unfavourable sign: it was a median of 8-fold and 3-fold in the patients with a median survival of 7 and 16 months, respectively. During treatment, sICAM-1 levels paralleled with those of sIL-2R. There was major intraindividual and interindividual variation in serum IL-6 and IL-8 levels with no distinctive kinetic pattern. Thus, no definite conclusions could be drawn. However, it seems worthwhile to measure IL-2, sIL-2R and sICAM-1 during immunotherapy; their prognostic value should be further evaluated in a larger patient population.

Effects of malignancy and interleukin-2 infusion on gut macromolecular permeability

OBJECTIVE

Enhanced gut permeability has been shown in patients with advanced malignancy. The dramatic inflammatory shock syndrome produced by high-dose interleukin-2 immune therapy could further change gut barrier function. This study measured the effect of advanced renal cell carcinoma and malignant melanoma, and interleukin-2 treatment on gut permeability.

DESIGN

Nonrandomized, controlled study.

SETTING

University hospital.

PATIENTS

Adults with metastatic, unresectable renal cell carcinoma or metastatic, malignant melanoma, and normal volunteers.

INTERVENTIONS

Gut permeability was measured in patients with renal cell carcinoma or malignant melanoma before and during interleukin-2 infusions, using polyethylene glycol 3350 and polyethylene glycol 400. The polyethylene glycols were administered orally within 48 hrs of interleukin-2 therapy and the 24-hr urine excretions were measured.

MEASUREMENTS AND MAIN RESULTS

Increased permeability was seen in the baseline state of these patients (ratio of polyethylene glycol 3350 to polyethylene glycol 400 = 1.1 +/- 0.7 x 10(-2)) when compared with normal volunteers (ratio = 0.48 +/- 0.2 x 10(-2); p < .05). However, after interleukin-2 treatment, no further increase in permeability was seen (ratio = 1.4 +/- 0.8 x 10(-2)).

CONCLUSIONS

Gut permeability to polyethylene glycol 3350 is enhanced in advanced malignancy. High-dose interleukin-2 therapy does not further increase permeability of the gut.

Soluble interleukin-2 receptor alpha is elevated in sera of patients with benign ovarian neoplasms and epithelial ovarian cancer

BACKGROUND

Previous studies have established that soluble interleukin-2 receptor alpha (sIL-2R alpha) levels are elevated in ascites and sera from individuals with advanced ovarian cancer (International Federation of Gynecology and Obstetrics [FIGO] Stage III/IV). This study was undertaken to evaluate sIL-2R alpha levels in individuals with benign ovarian neoplasms and early stage ovarian cancer (FIGO Stage I/II). Comparison with CA 125 levels was performed to assess screening potential.

METHODS

Sera from 92 healthy individuals, 61 with benign adnexal masses, 12 patients with FIGO Stage I/II ovarian cancers, and 27 patients with FIGO Stage III/IV ovarian cancers were assayed for sIL-2R alpha by enzyme-linked immunosorbent assay and CA 125 by radioimmunoassay.

RESULTS

The mean serum sIL-2R alpha levels for benign pelvic masses, and Stage I/II and Stage III/IV epithelial ovarian cancer were 1507 +/- 82, 1631 +/- 274, and 2596 +/- 384 U/ml, respectively. The difference between mean serum sIL-2R alpha levels in individuals with benign adnexal masses and Stage III/IV epithelial ovarian cancer was statistically significant (P < 0.05). In addition, of the four individuals with FIGO Stage I/II ovarian cancer who had CA125 levels below 35 U/ml, the accepted upper limit of normal, three patients had elevated serum sIL-2R alpha levels. Eleven of 12 patients (92%) with potentially curable Stage I/II disease had elevated serum levels of either sIL-2R alpha or CA125 and 8 of 12 (67%) had elevations of both sIL-2R alpha and CA125. Sensitivity and specificity of a combination of CA 125 and soluble IL-2R alpha were 88.5% and 27.1%, respectively.

CONCLUSION

Soluble interleukin-2 receptor alpha levels do not appear to differentiate between benign adnexal lesions and early malignancy; however, measurement of sIL-2R alpha levels in combination with CA125 warrants further evaluation to determine if together they will identify individuals with Stages I and II ovarian cancer.

Serum-soluble interleukin-2 receptor concentrations in patients with gastric cancer

BACKGROUND

Serum concentrations of soluble interleukin-2 receptor (IL-2R) were found to be high in patients with autoimmune diseases, lung cancer, malignant lymphoma, tuberculosis, and other diseases. Serum-soluble IL-2R was evaluated as a tumor maker in patients with gastric cancer.

METHODS

Preoperative concentrations of serum-soluble IL-2R were examined in 40 patients with gastric cancer. The authors investigated the correlations of serum-soluble IL-2R concentrations with various characteristics of this cancer (disease stage, gross appearance, depth of the tumor, lymph node metastasis, liver metastasis, peritoneal metastasis, histopathologic grade, serum carcinoembryonic antigen (CEA), alpha-fetoprotein (alpha-FTP), carbohydrate antigen 19-9 (CA19-9), and immunosuppressive acidic protein (IAP). Serum soluble IL-2R concentrations were measured with an enzyme-linked immunosorbent assay.

RESULTS

Levels of serum-soluble IL-2R in patients with gastric cancer were significantly higher than those of normal control subjects. Serum concentrations of IL-2R in patients with lymph node metastasis were also significantly higher than those of patients without lymph node metastasis. There were no significant differences in histopathologic findings (grade, lymphatic invasion, venous invasion). Moreover, serum concentrations of soluble IL-2R in patients who were IAP positive were significantly higher than those who were IAP negative.

CONCLUSIONS

Preoperative serum-soluble IL-2R concentrations in patients with gastric cancer reflect the occurrence of regional lymph node metastases. Preoperative evaluation of serum soluble IL-2R concentrations may be a valuable parameter of indicating the probability of lymph node metastasis preoperatively.

Progression mechanisms in colon cancer: soluble interleukin-2 (IL-2) receptor, IL-2 plus anti-CD3 proliferative response and tumour stage correlations

Soluble interleukin-2 receptor (sIL-2R) levels have been found to be elevated in several clinical conditions, including disseminated solid neoplasms, whereas they are generally within the normal range in patients with locally limited neoplastic disease. The aim of the present study was to examine this in our colon cancer patients, and to assess if this situation can affect the in vitro activation of peripheral blood mononuclear cells (PBMC), examining the proliferative response to IL-2 and anti-CD3 monoclonal antibody, the IL-2 serum levels and the PBMC phenotype. The results show that sIL-2R levels were significantly correlated with the stage of the disease, showing an increase from stage I to stage IV; moreover, it is worth noting that the proliferative response to IL-2 plus anti-CD3 is significantly higher than to IL-2 alone in stage IV, without significant alteration in the numerical presence of T and natural killer cells. So it seems that in the peripheral blood of patients, connected with the disease progression, are present cellular populations showing a different response to activation, and that T cells acquire a better response condition than NK. Thus, since the T cellular population includes the tumour-specific cytotoxic precursor cells, this should be helpful for its tumour regressive activity, but it is conceivable that this population cannot perform its functions, owing to a deficiency in responsiveness of the specific ThCD4+ subpopulation.

The effect of radiation therapy on immune function in patients with squamous cell lung carcinoma

The immune response is impaired in patients with malignancy, and radiation therapy (RT) can exacerbate the cancer induced-attenuation of immune response. In order to search for the fine mechanisms behind the RT-induced attenuation of cell-mediated immune response, we measured the number of lymphocytes in peripheral blood, its subsets, and lymphoblast transformation induced by phytohemagglutinin (PHA), purified protein derivatives (PPD), mitogenic monoclonal antibody anti-CD3, and mitogenic combination of anti-CD2 antibodies 9-1 and 9.6 before and after RT in 19 patients with squamous cell lung cancer. Radiation therapy significantly decreased the total numbers of lymphocytes, CD-3, CD-4, and CD8-positive lymphocytes in peripheral blood. However, RT did not change the percentages of lymphocytes and its subsets. Radiation therapy increased the percentage of interleukin 2 (IL-2) receptor-positive lymphocytes, and RT significantly decreased in vitro lymphoblast transformation by PHA, PPD, or monoclonal antibodies to T-cell surface antigens (anti-CD2 or anti-CD3). In vitro incubation with IL-2 did not increase lymphoblast transformation by anti-CD3 before RT but significantly increased after RT. In conclusion, we suggest that one of the fine mechanisms behind the RT-induced suppression of immune responsiveness of patients with lung cancer is a defect in IL-2 synthesis by lymphocytes.

Serum soluble interleukin-2 receptor in colorectal cancer

Preoperative serum soluble interleukin-2 receptor (IL-2R) levels were measured in patients with colorectal cancer, and correlated with various factors as stage, lymph node metastasis, liver metastasis, grade, serum CEA and IAP (immunosuppressive acidic protein). The levels of serum soluble IL-2R in Dukes stage C were significantly higher than in normal control and in Dukes stage A. Serum levels were also significantly higher in patients with lymph node metastasis than in patients without such metastasis, and in IAP positive patients compared to IAP negative patients. Preoperative serum IL-2R levels thus seem to reflect the stage of the disease.

Serum soluble interleukin-2 receptor alpha levels in patients with gynecologic cancers: early effect of surgery

PROBLEM

To determine the early effect of abdominal cytoreductive surgery on serum soluble interleukin-2 receptor alpha (sIL-2R alpha) levels in patients with ovarian and cervical cancer, and to determine if the extent of cytoreduction correlated with the changes in serum sIL-2R alpha.

METHOD

Thirty-nine patients with gynecologic cancer had serum sIL-2R alpha measured by enzyme-linked immunosorbent assay before abdominal cytoreductive surgery and once in the early postoperative period.

RESULTS

Only patients with advanced epithelial ovarian cancer had elevated preoperative serum sIL-2R alpha levels. In 20 of 25 ovarian cancer cases (80%) and 10 of 14 cervical cancer cases (71.4%) the postoperative serum sIL-2R alpha levels exceeded the preoperative level (P = .003 and P = .011, respectively). Overall, the mean postoperative serum sIL-2R alpha level was greater than the preoperative level (P = .0001).

CONCLUSION

Patients with early stage gynecologic cancer did not have elevated serum sIL-2R alpha levels before surgery. In the early postoperative period the serum sIL-2R alpha level was increased, which may be a nonspecific response to the trauma of surgery. Soluble IL-2R alpha may be one of the factors responsible for the immunosuppression in the early postoperative period, but may also herald a surge of activated T cells.

Soluble interleukin-2 receptor in Sézary syndrome: its origin and clinical application

Soluble interleukin-2 receptor (sIL-2R) serum levels were evaluated in Sézary syndrome (SS), mycosis fungoides, non-epidermotropic T-cell lymphomas, inflammatory skin diseases (eczema, psoriasis and lichen planus) and benign erythroderma. All groups displayed mean values significantly higher than controls, and values in SS were also significantly higher than those in the other diseases investigated. Follow-up of 17 SS patients showed that serum sIL-2R correlated with the clinical course of the disease and with other haematological parameters (absolute number of circulating Sézary cells, lactic dehydrogenase). Culture experiments demonstrated that, in contrast with other haematological disorders, highly enriched resting Sézary cells were unable to release sIL-2R, and failed to release normal amounts even after mitogen stimulation. Nevertheless, the leukaemic burden, together with the activation and consequent CD25 expression of leukaemic lymphocytes infiltrating the skin, may justify the hypothesis of a neoplastic sIL-2R source. To further support this hypothesis, the highest sIL-2R values were found in patients with advanced disease, in which normal reactive lymphocytes were dramatically reduced.

The expression and biological activity of IL-2 receptor on a human pancreas cancer cell line

To ascertain whether the tumor cells can regulate the host immune systems through the production of the cytokines or their receptors, we examined the expressions of tumor necrosis factor alpha (TNF alpha), tumor necrosis factor beta (TNF beta), interleukin 2 (IL-2) and interleukin 2 receptor alpha chain (IL-2R alpha) on the human cancer cell lines by Northern blot analysis. We used K562 (leukemia cell line), MCF-7 (breast cancer cell line), LS180, HT29 (colon cancer cell lines), SH101 (gastric cancer cell line) and PH101 (pancreas cancer cell line). Expressions of TNF alpha, TNF beta and IL-2 mRNA were not detected in any of the tumor cell lines. However, 1.4 and 3.5 kilobases of the IL-2R alpha mRNA were expressed in the PH101 cells, but not in the other five cell lines. Furthermore, IL-2R alpha was detected on the cell surface of the PH101 cells by the flow-cytometric analysis with an anti-IL-2R alpha monoclonal antibody. Interestingly, the soluble IL-2R alpha (sIL-2R alpha) was found in the conditioned media obtained from the PH101 cell culture with a sandwich enzyme immunoassay. Moreover, the sIL-2R alpha secreted from the PH101 cells blocked the IL-2 dependent lymphocyte proliferation. These results indicate that the expression of IL-2R alpha on PH101 might suppress the IL-2 induced lymphocyte proliferation.

Chronic Effects of Subcutaneous Interleukin-2 Therapy on Soluble Interleukin-2 Receptors in Advanced Small Cell Lung Cancer

The increase in IL-2 receptor serum levels is one of the most typical changes in immune parameters during IL-2 cancer immunotherapy. To better define the effects of prolonged IL-2 injection on SIL-2R levels, we evaluated 7 advanced small cell lung cancer patients who received IL-2 subcutaneously at a daily dose of 9x106 IU/m2/12h for two days followed by 3x106 IU/m2/12h for 18 days (5 days/week for 4 weeks). Moreover, four patients were also evaluated during the second IL-2 cycle. Venous blood samples were drawn before and at weekly intervals during IL-2 therapy. Mean SIL-2R serum levels rapidly increased with the start of IL-2 injection, and they were signicantly higher than the baseline levels throughout the immunotherapy cycle. The increase in mean SIL-2R levels was higher in patients with progressive disease than in those with response or stable disease, but the difference was not significant. Finally, the increase in mean SIL-2R concentrations during the second IL-2 cycle was not significantly different from that seen during the first one. The present study confirms that IL-2 administration determines an evident increase in SIL-2R levels; moreover, it would demonstrate that re-exposure to IL-2 after a rest period does not induce a more pronounced SIL-2R release.

Soluble interleukin-2 receptor levels in patients with malignant melanoma and renal cell cancer

Soluble interleukin-2 receptor (sIL-2R) levels were measured in sera from 33 patients with metastatic malignant melanoma and 14 patients with metastatic or advanced renal cell cancer. Significantly elevated levels were found in both groups compared to 30 healthy controls. No correlation was found between the levels of sIL-2R and clinical parameters such as disease-free interval and tumour burden. Neither was there any correlation between receptor-levels and survival. This contrasts with the observations in lymphoma patients, but is in accordance with findings in other solid tumours. sIL-2R is possibly a marker of the host immune response to the tumour, but further investigations are needed to see if it has any predictive value concerning prognosis or response to immune therapy.

Soluble interleukin 2 receptor in lung cancer. An indirect marker of tumor activity?

Circulating levels of the soluble interleukin 2 receptor (sIL-2R) could provide an in vivo measure of the immunologic response to human tumors. We performed a total of 326 sIL-2R serum assays in 126 patients with lung cancer (67 at diagnosis, 59 during and after treatment), 112 patients with pulmonary benign diseases, and 63 voluntary healthy subjects. Patients with lung cancer had a median value of sIL-2R of 791 U/ml, which was superior to that of both controls (398 U/ml, p less than 0.001) and patients with noninflammatory benign diseases (583 U/ml, p less than 0.02). However, infectious pulmonary disorders, such as tuberculosis and pneumonia, were associated with the highest values of the substance (median, 1150 U/ml; p less than 0.001). At the diagnosis of lung cancer, sIL-2R correlated neither with the stage of disease nor with the cell type. On the contrary, posttreatment levels of the receptor were significantly related to disease status (RO = .41, p less than 0.002), particularly in the subgroup of nonsurgical patients (RO = .48, p less than 0.001). Patients with abnormal sIL-2R levels had a nearly significant reduction in survival as compared with patients with normal values (p less than 0.1). Measurements of sIL-2R could be useful in monitoring patients under treatment for bronchogenic carcinoma, as well as in prognostication. In this setting, sIL-2R might open a new class of biologic markers, providing information that is complementary to those of the more classic tumor-derived markers.

Effect of antitumor surgery on soluble interleukin-2 receptor serum levels

Surgically induced immunosuppression may play a role in cancer, because of the possible existence of micrometastases at the time of surgical removal of tumors. Antitumor immune reactions are mediated by interleukin-2 (IL-2). IL-2 acts on a specific IL-2 cell surface receptor; moreover, a soluble form of IL-2 receptor (sIL-2R) can be released in the blood. This study was carried out to evaluate the effect of surgery on sIL-2R serum levels in patients with operable solid tumors. A total of 48 patients with cancer and 11 controls who underwent major surgery for non-neoplastic disease were evaluated before and 7 days after surgery. Serum mean levels of sIL-2R were significantly higher after than before surgery in both the cancer and control groups. No correlation was seen between surgery-induced changes in sIL-2R and in T lymphocyte subsets. Because of its capacity of binding to IL-2, the increased blood concentrations of sIL-2R could reduce the IL-2 availability and negatively affect antitumor immune reactions.

The biological significance of soluble interleukin-2 receptors in solid tumors

In an attempt to further understand the biological significance of soluble IL-2 receptors (sIL-2R) in solid tumors, we have evaluated 160 cancer patients (breast: 40; lung: 66; colon: 18; stomach: 22; uterine cervix: 14) and 58 healthy subjects, as controls. Serum mean levels of sIL-2R, measured with an enzyme immunoassay, were significantly higher in cancer patients than in controls. Metastatic cancer patients showed significantly higher values than the non-metastatic ones; this difference was significant in all tumor histotypes, except small cell lung carcinoma. Moreover, in 15 patients in whom sIL-2R were evaluated either before or after radical surgery, a significant surgery-induced increase in sIL-R mean values was seen. Finally, the chemotherapy-induced rise in sIL-2R appeared to be associated with a lack of clinical response. These results seem to suggest that sIL-2R may be a marker of host biological response in patients with solid tumors, the significance of which needs further investigation.

Lack of Changes in Soluble Interleukin-2 Receptor Serum Levels during Chemotherapy-induced Lymphocyte Damage

The biological significance of soluble IL-2 receptors (sIL-2R) is still unknown; in particular, it is not yet clear whether their increase in the blood may reflect activation of immune cells, or whether it is related to an immune dysfunction. To investigate this problem, we evaluated serum levels of sIL-2R before and after administration of a highly lymphocytolitic chemotherapy (FEC: fluorouracil, epirubicin, cyclophosphamide) in a group of 6 patients with advanced breast cancer. SIL-2R were analyzed in relation to lymphocyte number. Absolute mean number of lymphocytes was significantly lower after than before chemotherapy. On the contrary, no significant difference was seen in sIL-2R mean levels, and no significant correlation was observed between changes in sIL-2R and in lymphocyte number following chemotherapy. These results would exclude that sIL-2R may simply be due to a passive release following lymphocytic damage.

Interleukin-2 Receptor Positive Cells and Circulating Soluble Interleukin-2 Receptors in Patients with Solid Tumors are not Correlated

Activated lymphocytes can release a soluble form of IL-2 receptor (sIL-2R), which retains the capacity to bind IL-2. Abnormally high values of sIL-2R have been observed in patients with advanced solid tumors. In an attempt to further understand the biological significance of sIL-2R in solid tumors, this study investigated the relation between sIL-2R and Tac-positive cells. sIL-2R serum levels and Tac-positive cells were determinedin 18 patients with solid tumors metastatic, 108 non-metastatic. Tumor types were: breast 7; lung 6; colon 2; stomach 1; testis 1; larynx 1. No correlation was found between circulating sIL-2R values and Tac-positive cells, and there was no difference between Tac-positive cell mean number in patients with high and normal sIL-2R levels. These preliminary results suggest that different mechanisms are responsible for sIL-2R release in the blood and IL-2 receptor expression on the immune cell surface.