Detection of circulating immune complexes by the inhibition of anti-antibody

Induction in human allograft recipients of unresponsiveness to anti-lymphocyte globulin

The observations presented here confirm previous reports that polyclonal ALG prepared at the University of Minnesota or ATGAM of The Upjohn Co., administered as described, rarely induced sensitization of patients to the horse gamma globulin. In addition, the phenomena of transient antibody production prior to the onset of unresponsiveness and the induction of unresponsiveness in individuals with preexisting antibodies were observed.

Nature of immune complexes in autoimmune chronic active hepatitis

Immune complexes containing antinuclear antibodies have been observed in autoimmune chronic active hepatitis. Using a library of nuclear constituents (deoxyribonucleic acid, small nuclear ribonucleoproteins, and histones), we analyzed the antigens involved in formation of immune complexes. Immune complexes were defined in dissociation experiments, and after separation under dissociating conditions. Immune complexes composed of histones and immunoglobulin G were observed in four of nine immune complex-positive autoimmune chronic active hepatitis sera. Immune complexes containing the small nuclear ribonucleoprotein U1-RNP and immunoglobulin G were observed in two additional samples. Kidney eluates obtained from 2 patients with autoimmune chronic active hepatitis and membranous glomerulonephritis revealed enrichment of anti-U1-RNP, suggesting specific deposition of this antibody in complexed form. Circulating immune complexes containing histones were observed only in patients with autoimmune chronic active hepatitis-associated sicca syndrome; those containing U1-RNP were restricted to patients with autoimmune chronic active hepatitis associated with kidney disease.

Demonstration of immune complexes containing the ribonucleoprotein antigen Ro in primary biliary cirrhosis

We have previously demonstrated circulating and tissue-fixed immune complexes containing the small cytoplasmic ribonucleoprotein antigen Ro and immunoglobulin G (IgG) in a case of sicca syndrome associated with primary biliary cirrhosis. To establish the overall prevalence of such complexes in liver disease, we performed dissociation experiments under conditions of Ro antigen excess. Of the diseases tested, Ro-containing immune complexes were restricted to cases with primary biliary cirrhosis. Sera from 29 of the 47 patients with primary biliary cirrhosis (60%) showed IgG-containing immune complexes; 10 of the 29 sera samples (34%) positive for IgG-containing immune complexes exhibited immune complexes composed of Ro and anti-Ro IgG. These complexes sedimented predominantly as intermediate or large aggregates and were encountered most frequently in cases with extra-hepatic features.

Lack of association of rheumatoid factor with either circulating immune complexes or tumor burden in cancer patients

The frequency of rheumatoid factor (RF) seropositivity and the frequency of association of RF with immune complex (IC) elevation were determined in 72 patients with a variety of solid tumors, in 78 patients with IC-associated diseases, 27 patients with non-IC-associated diseases, and in 31 normal healthy controls. The frequency of RF positivity in cancer patients (31%) was virtually identical to that in patients with IC-associated diseases (28%), and did not differ significantly from that seen in patients with non-IC-associated disease (15%). Whereas IC elevation was clearly related to tumor progress, RF was not. RF and IC status also appeared to be unrelated to each other, not only in cancer patients, but in patients with other diseases as well. The results do not support the concept that RF reflects progressive tumor growth or an immune response to IgG-containing immune complexes.

Immunotherapy in the treatment of acute myelogenous leukemia (AML): rationale, results and future prospects

Patients with AML in complete remission (CR) are immunosuppressed; remission lymphocytes of at least a part of the patients are able to recognize autologous leukemic blasts; the CR represents a minimal residual disease. Thus, important conditions for a potentially successful active immunotherapy are given. Results of most earlier randomized trials on immunotherapy revealed some, but limited benefit with respect to survival. Encouraging effects, however, have been achieved by immunizing CR patients with high-dose neuraminidase-treated allogeneic blasts. Because these data have not been confirmed until now we recently initiated a randomized study utilizing identical treatment protocols. The preliminary results of the ongoing study still do not allow to draw any firm conclusions. Specific monoclonal antibodies or autologous cytotoxic T-cells may be useful tools for future immunotherapy of AML.

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.

Determination of immune complexes in sera from dogs with various diseases by mastocytoma cell assay

Canine immunoglobulin G complexed with particulate or soluble antigen can bind to the Fc receptors on the mastocytoma cells. Attachment of immune complexes composed of immunoglobulin G and soluble antigen (ovalbumin) to mastocytoma cells was detected by an inhibition of rosette formation with indicator cells (sensitized sheep erythrocytes). Therefore, canine circulating immune complexes may also attach to mastocytoma cells and inhibit rosette formation (mastocytoma cell assay). Sera from 326 dogs with various diseases and from 50 clinically normal dogs were assayed for immune complexes. The incidence of immune complexes in sera from normal dogs was 6% as compared with 25% in dogs with various diseases. The immune complexes were demonstrated in 37% of sera from dogs with various neoplastic diseases, 40% of sera from dogs with diabetes, 24% of sera from dogs with hypothyroidism, 50% of sera from dogs with mycotic disease, 75% of sera from dogs with arthritis, 38% of sera from dogs with kidney disorders, 40% of sera from dogs with neurological diseases, 45% of sera from dogs with various parasitic diseases, and 27% of sera from dogs with liver disorders. Only 19% of sera from dogs admitted to the hospital for various surgeries gave positive results. The incidence of the positive sera from dogs with various diseases is discussed in regard to their counterparts of human diseases.

Are immune complexes a factor in the pathogenesis of otitis media with effusion?

The authors investigated the presence of IgG-containing immune complexes in middle ear effusions as well as in middle ear mucosa and mastoid mucosa using the Raji cell radioimmunoassay (RIA), the inhibition of anti-antibody, and direct immunofluorescence tests. The Raji cell RIA showed positive results in two of 15 concentrated middle ear effusions but in none of 26 unconcentrated samples. The anti-antibody inhibition assay revealed immune complexes in two of 26 unconcentrated fluids. Thus, with two assays for soluble immune complexes, only four of 63 samples (6 per cent) were positive. Direct immunofluorescence of middle ear mucosa and mastoid mucosa resulted in localization of IgA and IgG in the plasma cells of the middle ear mucosa. A concomitant immunofluorescent staining for complement or immunoglobulin deposits along the basement membrane of the epithelium and/or blood vessels was not observed in 37 biopsy specimens. These findings do not support the concept that immune complexes are involved in the pathogenesis of otitis media with effusion.

Soluble immune complexes in human disease

The great variety in biochemical properties of immune complexes occurring in human and animal disease states has made the detection of such complexes a difficult task. Variability in immune complex size, specificity, and interaction with humoral or cellular receptor systems, such as complement and phagocytes, suggests different pathogenic properties. The introduction of radioimmunoassays and the recently improved knowledge of the immune complex-receptor interactions have lead to the description of a large number of detection procedures, which in turn has widened the catalogue of diseases associated with immune complexes. This widespread occurrence of soluble immune complexes has lead many investigators to think that such complexes may occur either as a transient physiological phenomenon, important for fast clearance of the antigen, or as primary pathogenic factors triggering inflammatory reactions. Among the 50 procedures for immune complex detection known today, the article will select some pertinent tests, which will be discussed with respect to their specificity, sensitivity, and reproducibility. Furthermore, it is well known that when applied to the study of a patient group with one particular immune complex disease, various tests will result in different percentages of patients having complexes. This observation is due to differences in the underlying principle on which the various tests are based. Thus immune complexes must be further characterized with respect to their size, to the antibody class or specificity involved and, most difficult, to the antigenic specificity which participates in the complex. Recent advances in such experimental characterization of immune complexes in vitro and in the clinical evaluation of patients with complement activation associated to the presence of immune complexes will be discussed.

The L1210 assay for immune complexes: application in cancer patients and correlation with disease progress

Immune complexes (ICs) were determined by the non-complement-dependent L1210 radioimmune assay on 132 serum samples collected from 53 patients with a variety of cancers. Both the mean IC levels and frequency of positive tests were significantly greater in cancer patients (mean = 96 +/- 100 microgram/ml, 46% positive) than in a control group of 67 normal healthy blood donors (mean = 39 +/- 15, 3% positive). When cancer patients were assorted into groups by disease progress, those with large or progressing tumors had significantly higher mean values (136 +/- 129) and frequency of positives (75%) than those with small or regressing tumors (58 +/- 18, 22% positive). In lung cancer patients, IC levels showed a strong inverse correlation (rs = -0.903) with survival time in patients who died, and appeared to be a better prognostic indicator than performance status (Karnofsky scale) at time of diagnosis. Serial IC measurements taken on several patients showed a decrease in levels concomitant with a favorable response to cytoreductive therapy, sustained normal levels during periods of prolonged remission, and a rise to elevated levels with (and sometimes preceding) documentation of new metastases.

Studies on immune complexes in rheumatoid arthritis

Sera and synovial fluids of patients with rheumatoid arthritis were studied for immune complexes by means of the anti-antibody inhibition test; approximately 40% of these specimens were shown to contain immune complexes. To study the nature of antigens participating in the formation of complexes under investigation, the anti-antibody inhibition test was repeated after addition of various soluble antigens to the complex-positive rheumatoid arthritis sera. This resulted in conversion of some sera from inhibitory to noninhibitory. It was found that of 15 positive rheumatoid arthritis sera, 7 had complexes formed by heterophile, Hanganutziu-Deicher antigen and of 12 positive sera tested, 2 had complexes formed by human IgG.

The L1210 radioimmune assay for detecting circulating immune complexes

A radioimmune assay for the detection and quantitation of circulating immune complexes has been developed which employs the L1210 murine leukemia cell. The assay is based upon the binding of immune complexes to the L1210 through its Fc receptor followed by quantitation of the complexes with an 125I-labelled anti-IgG. The radioactivity of the cell pellet is referred to a standard curve generated by incubating the L1210 with known amounts of heat aggregated IgG (AIgG). 7S IgG of three species (human, canine, murine) do not bind significantly to the L1210 in contrast to the respective AIgG. The assay readily distinguishes between sera of healthy individuals and sera of individuals (human and canine) with diseases known to be associated with circulation immune complexes (i.e., systemic lupus erythematosus, HBAg positive acute hepatitis). The L1210 radioimmune assay is capable of detecting as little as 5 micrograms of immune complexes per ml of serum in all three species tested. The assay possesses several advantages over those currently employed, the most notable being the ability of the L1210 cell to detect immune complexes irrespective of their complement fixing properties.