Circulating immune complexes in patients with bone tumours

Identification of acute-phase proteins (APP) in circulating immune complexes (CIC) in esophageal cancer patients' sera

The occurrence of increased circulating immune complexes (CIC) in sera of patients with esophageal cancer and their usefulness for diagnosis and prognosis have not been demonstrated. Circulating acute-phase proteins (APP) related to esophageal cancer have been described but without any association with CIC. This is a study to measure CIC, C-reactive protein (CRP), and alpha 1-acidic glycoprotein (AAG) in pretreatment esophageal cancer sera and to analyze the presence of both APP associated with these CIC. Increased CIC levels were found in 57% of sera from esophageal cancer patients; elevated CRP was detected in 87% and AAG in 47%. Western blot analysis showed the presence of CRP and AAG in CIC-derived fractions. We conclude that: (1) CIC, CRP, and AAG are elevated in esophageal cancer sera; (2) they may be considered possible useful clinical parameters in pretreatment esophageal cancer patients; (3) these APPs appear in CIC precipitates and may possibly be involved in their composition.

Quantitative determination of retrovirus-specific immune complexes

ELISA methodology was adapted to measure antigen-specific immune complexes (ASIC) containing retroviral antigens. Using ICs artificially generated from MuLV gp70 and monoclonal antibodies against gp70 we showed that ICs can be quantified by measuring the levels of antibody and antigen and comparing these to the total content of ICs. Furthermore, this method permits determination of the composition of ICs containing an excess of antigen or antibody (i.e., small or large complexes). The levels of the ASIC were correlated with the levels of ICs containing undefined antigen components as determined by the C1q ELISA. Using this method it was possible to determine levels of MuLV gp70 specific ICs in various mouse sera.

Prognostic and pathogenetic implications of immune complexes in human cancer

The dynamic relationships of circulating immune complexes (CIC) and associated immune reactants to stage of disease and prognosis in cancer patients have been evaluated for malignant melanoma. Patients were divided into group I patients, with no evidence of disease at sample time; group II patients, with minimal tumor burden; and group III patients, with advanced metastatic disease. By means of single- and serial-sample determinations, we have demonstrated correlation of CIC concentration, size, and composition to tumor burden, disease progression, and high risk of disease recurrence. In view of the phenotypic heterogeneity of antigen expression in malignant melanoma, we have extracted, purified, and utilized melanoma-associated antigens (MAA) from CIC, and human oncofetal antigens (HOFA) from fetal liver cells, and reacted them with patients' sera in an in vitro model that simulates tumor burden changes. The observed changes in CIC concentration and lattice size upon reaction with MAA and HOFA demonstrated a significant (p less than or equal to 0.001) relationship to patients' in vivo tumor burden, as well as to the origin of serum and antigen involved. Our results suggest a homeostasis of CIC size and concentration to associated antibodies and antigens operational in malignant melanoma patients' sera. In addition, we have demonstrated how the monitoring of more than one immune reactant, characterization of CIC size and composition, and evaluation of resulting reequilibrium caused by in vitro addition of antigen or antibody, could allow for an improved assessment of humoral immunity and its related pathogenetic effects in cancer patients.

Immunologic enhancement of experimental metastasis in the rat

Using a series of immunologically cross-reactive metastatic tumor variants, we demonstrate that serum from animals bearing pulmonary tumor colonies possesses enhancing properties in the experimental metastasis (lung colony) assay. Enhancement is produced by chronic serum administration and promotes the growth of tumor cells arrested in the lungs which would not otherwise proliferate to form grossly detectable lung nodules. Tumor-bearer serum from animals with lung colonies derived from the most highly metastatic variant examined is shown to possess enhancing properties in both BD-IX(H-1d) and BD-IV(H-1d) rat strains, while tumor-bearer serum from animals with lung colonies derived from the less metastatic parent tumor cell line possesses enhancing properties in the BD-IX rat strain only. Removal of immunoglobulin from enhancing serum by affinity column chromatography simultaneously removes the enhancing factor(s), and enhancing activity correlates with the presence of increased levels of Clq-binding immune complexes in the serum. Serum levels of immune complexes are shown to be more elevated in serum from animals bearing lung colonies derived from the most highly metastatic variant. The enhancing moieties are shown to bind to concanavalin A, but not to staphylococcal protein A, and the active fraction elutes from concanavalin A-Sepharose with alpha-methyl-mannoside. Consideration of immunoprecipitation studies on whole and fractionated enhancing sera, along with studies on affinity purified isotype fractions reveals that the activity resides with antibodies of IgG2b subclass.

Circulating immune complexes in chronic myeloid leukemia patients at various stages of the disease

Circulating immune complexes (CICs) in sera from patients suffering from chronic myeloid leukemia (CML) at initial diagnosis, in 'remission', at relapse and in blastic crisis have been quantitated using fluid [125I]Clq binding assay in terms of per cent binding activity and microgram/ml aggregated human globulin (AHG) equivalents. The Clq binding activity (Clq-BA) has been compared within the groups of CML patients in different phases of the disease as well as with sera obtained from normal healthy donors. The results showed that the mean Clq-BA was significantly increased in CML patients at initial diagnosis (25.74 +/- 3.48, p less than 0.001), in relapse (53.36 +/- 6.9, p less than 0.001) and in blastic crisis (60.5 +/- 8.7, p less than 0.001) when compared to control sera. Sera of 'remission' patients showed significant decrease in Clq-BA when compared to sera collected in active phases of the disease, however, the values were still significantly higher (12.87 +/- 1.58, p less than 0.02) than those of normal healthy donors. When the levels of CICs as assessed by Clq-BA were compared with the WBC/blast counts of CML patients in chronic as well as blastic phase, it was noted that the variations in numbers of circulating leukemic cells do not correlate with the CIC levels. The significance of assessment of CIC levels in monitoring the disease in CML patients is discussed.

Nature of antigens and antibodies in immune complexes isolated by staphylococcal protein A from plasma of melanoma patients

Immune complexes (IC) were isolated from plasma of melanoma patients by absorption to staphylococcal protein A and subsequent elution with MgCl2. The isolated ICs were purified by precipitation with polyethylene glycol and sucrose density gradient ultracentrifugation after radioiodination with 125I. The purified ICs were dissociated and radiolabeled antigen/antibody components were separated by ultracentrifugation at low pH (2.6). Under these conditions, about 72% radioactivity of the purified IC remained in the light-density region as a wide band. After neutralization, 26%-60% radioactivity in the region of 5S sedimentation bound to immobilized autologous immunoglobulins, as opposed to a maximum of 23% to immobilized immunoglobulins from human normal serum. Significant levels (73%-77%) of radioactivity in 7S region bound to rabbit anti-human IgG immunobeads. Immunoprecipitation of the antigen fraction by allogeneic anti-melanoma and rabbit anti-melanoma antibodies followed by SDS-polyacrylamide gel electrophoresis revealed the presence of a fetal antigen (FA) and a melanoma tumor-associated antigen (TAA). In addition, the presence of auto-antigen(s) was indicated by using autologous antibody in immunoprecipitation. Immunoglobulins (IgG) isolated from purified IC bound to cultured melanoma, sarcoma, and normal fibroblasts, although the binding to sarcoma and normal fibroblasts could be inhibited by preincubation of isolated IgG with soluble FA but not with soluble melanoma TAA. Thus, results of this investigation provide evidence that circulating IC in melanoma patients are composed of at least IgG and different antigens, and some of these antigens are produced by their tumor.

Circulating immune complexes in chronic myeloid leukemia: turbidimetric measurement and two-dimensional electrophoretic analysis

A 3.75% polyethylene glycol -6000 mediated turbidimetric method was used for the estimation of levels of circulating immune complexes (CIC) in sera of normal human subjects and patients with chronic myeloid leukemia (CML). In terms of equivalents of heat-aggregated gamma globulin (eq.HAGG mg/ml serum), the mean levels of CIC were: 5.69 mg/ml (SD 4.78) in 81 normal human subjects; 22.63 mg/ml (SD 9.86) in 52 untreated CML patients; 7.61 mg/ml (SD 5.74) in 54 CML patients in remission; and 21.70 mg/ml (SD 8.15) in 18 CML patients in relapse. High CIC levels, thus, showed a significant association with the pretreatment -- and relapse -- status of the disease (p less than 0.001 and p less than 0.001, respectively). Though the levels decreased during remission, they were still significantly above the mean level in the controls (p less than 0.05). The CIC level-disease status relationship was clearly evident in the serial studies on 19 CML patients who donated serum samples prior to treatment as well as during remission. Two-dimensional electrophoretic analysis of the CIC samples revealed the presence of a polypeptide (mol. wt approx. 37,000 and pI approx. 5.8) in 10 out of 18 CIC samples from the untreated CML patients. Such a moiety was not detected in six CIC samples from normal subjects. The association of this polypeptide with CML gains support from the observation that in 5 CML patients, this moiety was present in the CIC samples obtained prior to treatment but absent in the samples subsequently obtained during remission.

Circulating immune complexes as "tumor marker" in hepatoma-bearing rats (Yoshida AH 130)

The presence of circulating immune complexes (CIC) in a large number of malignancies was investigated in relation to the activity, the extent and the clinical course of the tumor clone. The aim of this study was to explore the relation between CIC serum levels and tumor growth in rats bearing the 130 Yoshida ascites hepatoma. For the assay of C3biCIC levels all samples were tested by a new competitive immunoenzymatic test. Experiments carried out on normal rats and on hepatoma-bearing ones, showed that during tumor growth values of CIC serum levels expressed as percent coefficient of inhibition are significantly higher in hepatoma-bearing rats (mean = 60.2) than in the normal controls (mean = 29.5). Furthermore CIC level and tumor proliferation are strictly correlated r = 0.9559. In this view sequential measurements of CIC levels may be valuable in establishing diagnosis, estimating prognosis and monitoring the behavior of neoplasia.

Relationship between circulating immune complexes and urinary antigens in human malignancy

Urine samples obtained from patients with histologically proved melanoma and sarcoma were analyzed for the presence of tumor-associated antigens by complement fixation and enzyme immunoassay. Also, serum samples obtained during 24-hour urine collection from these patients were analyzed for circulating immune complexes by the complement consumption method and by the K562 radiometric assay. Of 36 cancer patients who were positive for urinary antigen (UA) by both assays, 28 (78%) were also positive for CIC in the two assays, six (17%) were positive in one of the two CIC-detection assays, and two (5%) were negative in both assays. Of 24 patients that were negative for CIC in both assays, ten (42%) were also negative for UA in both assays, i.e., complement fixation and enzyme immunoassay; 12 (50%) were negative by one of the two assays; and only two (8%) exhibited UA by both assays. This relationship was more striking for melanoma than sarcoma patients. In a melanoma patient whose samples were studied sequentially during his thermochemotherapy, the fluctuations in CIC and UA were parallel. These results suggest that excretion of tumor-associated antigen into urine is not an isolated phenomenon; rather, immune complex deposition in kidneys appears to cause glomerular damage which may allow the passage of the antigens into the urine.

Application of cultured human myeloid cells (K562) for detection of immune complexes in human sera

Cultured human myeloid cells (K562) are known to bear Fc receptors that bind with aggregated human IgG (AHG). These cells were used to develop a radiometric assay for detection and quantitation of immune complexes (IC) in human sera. The binding of AHG or in vitro-formed IC between keyhole lympet hemocyanin (KLH) and human anti-KLH to the K562 cells did not require complement. When the K562 radiometric assay was compared to the complement-consumption assay, the K562 radiometric assay could detect IC over a wider range of antibody:antigen ratios. The incidence and mean IC values detected by the K562 radiometric assay in sera from cancer patients and patients with connective tissue diseases (498 +/- 445 and 436 +/- 209 micrograms AHG equ/ml, respectively) were significantly higher than in sera from healthy volunteers (107 +/- 62 micrograms AHG equ/ml). The IC level among sera from cancer patients ranged from 1-3200 micrograms AHG equ/ml. Studies with a limited number of sera from melanoma and sarcoma patients revealed that the mean IC values were significantly higher in patients who had clinically detectable disease than in those with no evidence of disease. Since the K562 cells do not require complement to interact with AHG, the K562 radiometric assay may be potentially useful for detecting IC in pathologic sera which may or may not contain in vivo-bound complement components.

Immunoselection of tumor variants resistant to antibody-mediated cytotoxicity. Their immunologic and metastatic characterization

The immunological characteristics of two series of metastatic variants of restricted genetic origin were related to their lung-colony-forming potential. A series of metastatic variants was isolated from a tumor-cell population in which heterogeneity appeared following short-term in vivo passage, while a second series of variants were immunoselected in vitro for resistance to antibody-complement-mediated cell lysis. In the case of the first series, the sensitivity of the individual variants to cell-mediated and antibody-complement-mediated cytotoxicity appeared to be partly determined by the number and rate of loss of antibody-binding sites on the cell surface. These characteristics also correlated with the efficiency of experimental metastasis in the animal. We compared the results reported herein with our previous studies of nonimmune parameters for this series of metastatic variants, and we conclude that immunological differences can be important to the efficiency of lung-colony formation. However, in the case of the second series of variants, despite selection in vitro for resistance to antibody-complement-mediated cell lysis, the behavior of these variants in the lung colony assay could not be predicted by the immunologic parameters examined.

Circulating immune complexes in patients with benign and malignant colorectal tumours

Circulating immune complexes were measured using a modified Clq binding assay in 100 preoperative patients with colorectal cancer and in 52 patients with benign polyps. Sixty-one per cent of the patients with cancer and 49 per cent of the patients with benign polyps had elevated levels, as did 92 per cent of those with malignant polyps. There was no relation to a, the stage of the disease, with 10 out of 13 Dukes' A tumours (77 per cent) having increased levels; b, the degree of differentiation of the cancers; c, the tumour mass. However, cancers on the right side of the colon had significantly higher levels than rectal cancers.

Report on international comparative evaluation of possible value of assays for immune complexes for diagnosis of human breast cancer

There have been several reports on the possible value of measurements of circulating immune complexes for the diagnosis of human breast cancer. To begin to evaluate this possibility and the comparability of results among laboratories, a cooperative study was organized under the auspices of the International Agency for Research on Cancer and the National Cancer Institute (NCI) of the United States. Investigators from four laboratories performing assays for immune complexes were sent coded aliquots of serum specimens from the NCI-Mayo Clinic Serum Bank. The serum panel consisted of specimens from 30 patients with breast cancer (including 20 from untreated patients with resectable tumors), 30 preoperative patients with benign breast disease, and 30 normal women. Although some significant differences in levels of immune complexes between cancer patients and controls were seen, none of the assays had sufficient discriminatory capacity to support optimism about the diagnostic value of this approach. To relate the results with immune complexes to those with a widely used cancer marker, the same sera were also tested for levels of carcinoembryonic antigen (CEA). The CEA assay provided significant discrimination between cancer patients and normal donors but did not significantly discriminate between malignant and benign breast diseases.

Circulating immune complexes in patients with lung cancer

Sera from 41 patients with lung cancer and 41 age and sex-matched hospital inpatients with non-malignant disease were tested for the presence of immune complexes using the 125Iodine Clq binding test. All patients were untreated or had recurrences after surgery. An increased Clq binding activity was found in 34% of patients with lung cancer and 24% of patients with non-malignant disease. There was no significant association between increased serum Clq binding activity and histological tumour type or survival but there was an association with the extent of malignant disease. No patient with limited (state 1) disease had raised Clq binding activity but in 42% of patients with extensive disease it was increased. Increased Clq binding activity did not correlate with either an increased total white cell count of ESR. Measurement of Clq binding activity may be of value in serial monitoring of disease progress and response to treatment.