Circulating immune complexes and autoantibodies in lung cancer

Surface tension in human pathophysiology and its application as a medical diagnostic tool

Introduction: Pathological features of disease appear to be quite different. Despite this diversity, the common feature of various disorders underlies physicochemical and biochemical factors such as surface tension. Human biological fluids comprise various proteins and phospholipids which are capable of adsorption at fluid interfaces and play a vital role in the physiological function of human organs. Surface tension of body fluids correlates directly to the development of pathological states.

Methods: In this review, the variety of human diseases mediated by the surface tension changes of biological phenomena and the failure of biological fluids to remain in their native state are discussed.

Results: Dynamic surface tension measurements of human biological fluids depend on various parameters such as sex, age and changes during pregnancy or certain disease. It is expected that studies of surface tension behavior of human biological fluids will provide additional information and might become useful in medical practice. Theoretical background on surface tension measurement and surface tension values of reference fluids obtained from healthy and sick patients are depicted.

Conclusion: It is well accepted that no single biomarker will be effective in clinical diagnosis. The surface tension measurement combined with routine lab tests may be a novel non-invasive method which can not only facilitate the discovery of diagnostic models for various diseases and its severity, but also be a useful tool for monitoring treatment efficacy. We therefore expect that studies of surface tension behavior of human biological fluids will provide additional useful information in medical practice.

Dynamic surface tension and surface rheology of biological liquids

The paper presents results of dynamic and equilibrium surface tension measurements (using a maximum bubble pressure instrument) of serum and urine samples that were obtained from 80 healthy human of various sexes and ages. These data were compared with surface tension measurements of biological liquids obtained from patients suffering from malignant neoplasm of corpus uteri (n=5) and cervix uteri (n=31). In addition, surface dilatational rheology was determined on 32 samples using a drop shape method. The dilatational rheology data were compared with the dynamic surface tension data. Although some trends were found, no significant correlations exist between surface tension and rheology data and any of the disease states or stages. It is difficult to explain these findings in the framework of known mechanisms. However, our studies demonstrate that dynamic interface tensiometry of human biological liquids provide new insight into the biophysical behavior of these liquids, most likely reflecting compositional changes of them during ageing, the course of cancer and as a consequence of therapeutical interventions.

Studies on the application of dynamic surface tensiometry of serum and cerebrospinal liquid for diagnostics and monitoring of treatment in patients who have rheumatic, neurological or oncological diseases

Human biological liquids comprise various surfactants, which adsorb at liquid interfaces and lead to a variation in surface tension. The adsorption processes involving low molecular weight surfactants, proteins and phospholipids play a vital role in the physiological functions of the human organism, especially if large surfaces are involved (e.g., gas exchange in lungs, metabolism of kidneys, liver and brain). Dynamic surface tensiometric studies of biological liquids like serum and cerebrospinal fluid provide surrogate parameters that reflect surface tension phenomena. We provide dynamic surface tension data of serum and cerebrospinal fluid that were collected from healthy volunteers and patients with rheumatic, neurological or oncological diseases. Our studies indicate that dynamic surface tension data are helpful for diagnostic purposes and for monitoring of therapeutic interventions.

Characterization of a lung-cancer-associated auto-antigen

An antigen, protein X (Px), was purified from immune complexes isolated from malignant pleural effusions from patients with adenocarcinoma of the lung by EDTA treatment, PEG 8000 precipitation, protein A affinity chromatography, and Sephadex G-200 separation in the presence of 3 M NaCl. The purified antigen had a M(r) 17,000 by SDS-PAGE, and consisted of isoelectric species of pI 6.3 and 6.6. Purified Px recombined with Ig isolated from pleural fluids from patients with lung adenocarcinoma, but not with Ig from patients with breast carcinoma. Using an autologous human and heterologous chicken antibody, Px was found, by immunohistology, in the cytoplasm of some of the well-differentiated lung adenocarcinoma cells, but was not seen in normal lung or a variety of other malignant tissues. A liquid-phase competitive-inhibition RIA was developed. Over 30 ng/ml of Px were found in 9 of 15 pleural fluids from patients with lung carcinoma, none of 20 from patients with breast, ovary, stomach or colon cancer, and in 3 of 15 patients with unknown primary tumor. Our data suggest that Px may be a lung-cancer-associated autoantigen which can elicit a host humoral response in vivo.

Human lung cancer--a comparative study of the levels of circulating immune complexes in pulmonary blood draining the tumor area and peripheral venous blood

Our objective was to investigate whether low levels of circulating immune complexes (cICs) in peripheral venous blood of cancer patients could be due to removal of cIC released at the tumor site during passage to the peripheral veins. In 54 patients with primary lung cancer, we therefore compared the cIC levels as detected by 3 different assays in paired samples from the pulmonary vein draining the tumor area and from a peripheral vein. Only 6 of the 54 patients had significantly increased pulmonary vein cIC levels as compared to the corresponding peripheral vein levels. The peripheral vein levels of these 6 patients were all within the normal range, and in none of these patients was the difference between the 2 sites of analysis--although significant--of such a magnitude that the pulmonary vein cIC level appeared higher than the normal range, i.e., "positive" for cIC. Positive cIC levels were only found in 11% of lung cancer patients (irrespective of the site of measurement). Thus, our present data, together with our previous findings indicating no significant difference between peripheral venous blood cIC levels in cancer patients and normal controls, contradict the theory of tumor cells expressing new antigens resulting in the formation of tumor-associated cICs.

Primary lung cancer. A controlled study of preoperative and postoperative levels of circulating immune complexes

Three complement-dependent and one rheumatoid factor-dependent immune complex assays were used to analyze the sera taken before surgery from 70 unselected and previously untreated lung cancer patients, from 30 of them after surgery, and from 31 healthy controls. Plasma levels of complement split product C3d were also analyzed. The levels of circulating immune complexes (cIC) and C3d were essentially the same in samples taken from lung cancer patients before surgery and from healthy controls. By the four immune complex assays, increased levels were found in 0 to 10% of the preoperative lung cancer patients compared to 3% of the healthy controls (not significant). The postsurgical tumor, lymph node, metastasis (pTNM) stage of the lung cancer was not reflected in the levels of cIC or C3d. Paired comparisons of the cIC and C3d levels before and after surgery did not show significant differences. Thus, we found no evidence for the occurrence of cancer-related cIC in lung cancer patients.

The spectrum of complement-fixing antinuclear antibodies in patients with hepatocellular carcinoma

Sera from 230 hepatocellular carcinoma patients were tested for antinuclear antibodies by anticomplement immunofluorescence in 16 types of transformed, diploid or primary cells of human, monkey, chimpanzee or rat origin. As controls, we tested 85 sera from patients with chronic liver diseases, 48 sera from patients with nonhepatic cancers and 164 sera of normal controls. Exactly 11.2% of all cancer patients but only 3.6% of noncancer patients had complement-fixing antinuclear antibody that reacted with all substrates. Only sera from hepatocellular carcinoma reacted with subsets of the tumor cell substrates. These sera reacted with hepatocellular carcinoma cells and nonhepatic cancer cells (antitumor) or only with one or more of the human hepatocellular carcinoma cell lines, PLC/PRF/5, Hep3B and Mahlavu, that were derived from HBsAg-positive patients (antihepatocellular carcinoma). Three of these reacted only with hepatitis B virus DNA-positive cells (PLC/PRF/5 and Hep3B) that contained "hepatitis B-associated nuclear antigen," 1 reacted only with hepatitis B virus DNA-negative Mahlavu cells, 1 reacted with PLC/PRF/5 and Mahlavu and 3 reacted with all 3 cells. The nuclear antigen in Mahlavu was expressed as a homogeneous fluorescence that spared the nucleoli, was present in a lower percentage of cells than hepatitis B-associated nuclear antigen and was more thermostable than hepatitis B-associated nuclear antigen. However, it resembled hepatitis B-associated nuclear antigen in kinetics of expression and susceptibility to digestion with DNase, RNase and proteinase K. The nature of the nuclear antigens in the hepatocellular carcinoma cells is poorly understood but one possibility is that they may represent the expression of viral or tumor-related genes.(ABSTRACT TRUNCATED AT 250 WORDS)

Advantages of sequential polyethylene glycol (PEG) precipitations to isolate and analyze circulating immune complexes

The present report describes a new approach utilizing sequential polyethylene glycol 6000 (PEG) precipitations to isolate and analyze circulating immune complexes (IC). Two experimental systems were studied. First, IC were formed by adding labeled or unlabeled bovine serum albumin (BSA) to anti-BSA antiserum. Sequential precipitations with PEG concentrations ranging from 2 to 6.2 indicated that immunoglobulin (Ig) molecules were precipitated in all experimental and control sera tested. In contrast, optimal precipitations of IC (i.e., highest BSA/Ig ratio) were a function both of PEG concentration and of BSA/anti-BSA ratio (i.e., of IC size). Satisfactory IC purification was achieved by precipitation with appropriate PEG concentration followed by incubation with STaphylococcus aureus, Cowan I. Second, in preliminary experiments, the same procedure was applied to human sera. The findings paralleled those of the BSA/anti-BSA system. While PEG precipitated Ig in all sera tested, a potential antigen was found only in the most IC-positive serum, and only at the higher of the two PEG concentrations tested. From our data, we conclude that PEG concentrations needed to precipitate IC cannot be predetermined, as they are a function of the size and probably the nature of the IC studied. This limitation can be overcome by the systematic sequential precipitations which increase the chances of identifying antigens and decrease the risks of confusing antigen-antibody complexes and Ig aggregates.