Polymorphonuclear leukocytes stimulation by immune complexes. Assessment by nitroblue tetrazolium dye reduction

Alteration of macrophage function in AKR/J leukemic mice

Peritoneal macrophages from AKR/J leukemic mice, a strain which spontaneously develops a virally induced T-cell lymphoma between the age of 8-12 months, were used to study any possible changes in adherence, opsonization, phagocytosis, nitroblue tetrazolium (NBT) reduction and antibody-dependent cellular cytotoxicity (ADCC). Increased adherence, opsonization and phagocytosis of particles and impaired ADCC were found when these macrophages were compared with those from tumor-free BALB/c mice. Moreover, phagocytosis and NBT reduction in macrophages from AKR/J leukemic mice were also found to be increased when compared with macrophages from AKR/J mice in their preleukemic stage. The possibility that the decline in ADCC observed, in spite of the fact that the macrophages were activated and showed an increase in other functional aspects, may be responsible for the defective surveillance of macrophages in tumor development is also discussed.

Antigen presentation by chemically modified splenocytes induces antigen-specific T cell unresponsiveness in vitro and in vivo

We investigated the antigen specificity and presentation requirements for inactivation of T lymphocytes in vitro and in vivo. In vitro studies revealed that splenocytes treated with the crosslinker 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (ECDI) and soluble antigen fragments failed to stimulate significant proliferation by normal pigeon cytochrome c-specific T cell clones, suggesting that the chemical treatment inactivated full antigen presentation function. However, T cell clones exposed to ECDI-treated splenocytes and antigen in vitro were rendered unresponsive for at least 8 d to subsequent antigen stimulation with normal presenting cells. As predicted by the in vitro results, specific T cell unresponsiveness was also induced in vivo in B10.A mice injected intravenously with B10.A, but not B10.A(4R), splenocytes coupled with pigeon cytochrome c via ECDI. The antigen and MHC specificity of the induction of this T cell unresponsiveness in vitro and in vivo was identical to that required for T cell activation. These results suggest that nonmitogenic T cell recognition of antigen/MHC on ECDI-modified APCs results in the functional inactivation of T cell clones.

Suppression of in vitro lymphocyte proliferation in C57BL/10 ScN mice vaccinated with phase I Coxiella burnetii

The effect of inactivated phase I and phase II Coxiella burnetii whole cell vaccine (WCV) on the response of murine spleen cells to mitogenic and antigenic stimuli was evaluated in C57BL/10 ScN endotoxin nonresponder mice with an in vitro lymphocyte proliferation assay. Intraperitoneal injection of phase I WCV into mice resulted in marked and persistent suppression of the proliferative response of spleen cells to concanavalin A, phytohemagglutinin, and pokeweed mitogen. This response was time and dose dependent and was not associated with decreased lymphocyte viability. By using a standard dose of 100 micrograms of phase I WCV, suppression of mitogenic responsiveness was first detected 3 days postinjection, attained maximum levels by day 14, and persisted for longer than 5 weeks. Suppression of mitogenic lymphocyte proliferation also was demonstrated after inoculation of animals with viable phase I organisms. The observed hyporesponsiveness of spleen cells from phase I WCV-injected animals was not either the result of a shift in the mitogenic dose optimum or due to a change in the day of in vitro peak response. Spleen cells from phase I WCV-injected mice were negatively regulated with homologous antigen. Investigation of the mechanism of action of phase I WCV, with a 51Cr-release assay, and trypan blue dye exclusion showed that phase I WCV was not directly cytolytic or cytotoxic to spleen cells from normal or vaccinated mice. Phase II WCV did not induce significant mitogenic hyporesponsiveness or negative modulation of spleen cells. These findings extend the observations of adverse host responses associated with the phase I WCV and underscore the need to develop a microbial fraction which possesses protective potency but which lacks the propensity to induce deleterious tissue reactions and immunosuppression.

Evidence against a role for neutrophils in the clearance of small immune complexes

The activation of human neutrophils (PMN) by immune complexes (IC) consisting of tetanus toxoid and the corresponding human antibodies was studied by varying IC properties like size, antigen: antibody ratio, Fc density, etc. While Ag: ab ratio seemed to have some importance, especially when complement activation was allowed, size appeared to be the decisive factor. Surprisingly, good stimulation of PMN was obtained only with very large IC and no plateau was reached with increasing size. PMN activation even by these very large complexes was inhibited in the presence of physiological IgG concentrations, but only if complement was omitted. Generation of IC in the presence of serum, on the other hand, prevented the formation of IC sufficiently large for PMN activation. Finally, in an IC clearance experiment in mice using 125I-labelled human serum albumin and mouse antibody, no radioactivity was found associated with blood PMN in spite of a rapid clearance. It is concluded that PMN are probably not involved in the physiological clearance of IC if these are considerably smaller than opsonized microorganisms.

Neutrophil activation by immune complexes and the role of rheumatoid factor

Membrane activation of human neutrophils by preformed immune complexes and heat aggregated human gammaglobulins was studied by chemiluminescence. Strong neutrophil activation was found with human-albumin rabbit-antialbumin complexes prepared at equivalence, with maximal activation occurring in slight antigen excess. Furthermore different preparations of heat aggregated gammaglobulin which were of large size also showed similar activity. In contrast, heat aggregates of small size were inactive and blocked the chemiluminescent response found with larger active aggregates. A purified monoclonal rheumatoid factor with specificity for IgG modulated these responses when preincubated with preformed complexes or aggregates. Both enhancement of the neutrophil chemiluminescence response with inactive preparations and suppression of the response with highly active preparations were observed. Kinetic studies of the neutrophil chemiluminescent response varied with respect to the activating preparation, but were generally biphasic. This observation suggested an initial direct membrane activation followed by a more delayed response reflecting phagocytosis of complexes. We have demonstrated the direct activation of neutrophil chemiluminescence by laboratory preparations of immune complexes. The chemiluminescent responses observed were influenced by both the size and immunochemical properties of the activating complexes and by the presence of rheumatoid factor. These observations may have important implications in the immunopathogenesis of immune-complex-mediated diseases.

Phagocytosis and degradation of DNA-anti-DNA complexes by human phagocytes II. Influence of the size of the complexes

The influence was studied of the size of DNA-anti-DNA complexes on their capacity to induce phagocytosis and degradation by monocytes and neutrophils from human blood. An estimate of the size of the complexes was obtained by precipitation analysis, sucrose-gradient velocity sedimentation and filtration over Nucleopore filters. The results show that only those complexes are processes that precipitate in 15 min at 3000 x g. These complexes have an S value of more than 25000 and a diameter of more than 0.4 micrometer. Likewise, tetanus-anti-tetanus complexes also had to be precipitable in 15 min at 3000 x g to be processed by the phagocytes.

A modified spectrophotometric test for nitroblue-tetrazolium reduction of granulocytes and monocytes and its application for testing inhibition of monocytes by serum components in tumor patients

For evaluation of serum-factor involvement in monocyte function, we established a modified quantitative spectrophotometric-nitroblue tetrazolium (NBT) test. We investigated the stimulation of human peripheral monocytes and granulocytes by zymosan, endotoxin, and Corynebacterium parvum in vitro. In addition, polymorphonuclear neutrophil (PMN) function in a patient with non-Hodgkin lymphoma was studied during the course of polychemotherapy and intravenous application of Corynebacterium parvum (C. parvum). In non-Hodgkin lymphoma (n = 15) and bronchogenic carcinoma (n = 11) the NBT-reduction of autologous monocytes in presence of autologous serum in relation to a AB serum was decreased compared to a control group of age-matched healthy blood donors. The sera from patients with these neoplasms inhibited NBT-reduction of monocytes from healthy donors. This inhibition showed a correlation to the presence of immune complexes in patients with bronchogenic carcinoma.

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.

Monocytes and macrophages in malignant melanoma. III. Reduction of nitroblue tetrazolium by peripheral blood monocytes

Peripheral-blood monocytes from normal individuals and from patients with malignant melanoma reduce nitroblue tetrazolium (NBT). A quantitative assay for dye reduction was applied to 25 healthy donors and 31 patients with malignant melanoma. NBT reduction expressed as dye reduction per monocyte was significantly impaired in patients with disseminated disease, and they responded poorly to a phagocytic stimulus. Monocytes from patients with micrometastatic disease, however, showed normal resting NBT reduction but, following exposure to a suspension of latex-polystyrene, showed significantly greater NBT reduction than those from normal individuals. Since NBT reduction is an indirect measure of intracellular hexose-monophosphate-shunt activity we conclude that the monocytes from patients with minimal disease are in some way activated.

Granulocyte function in bacterial infections in man

The reduction of nitroblue tetrazolium (NBT) dye and the phagocytic and bactericidal activities of neutrophil granulocytes from 141 patients with bacterial infections and 141 controls have been examined and related to granulocyte morphology. In 115 patients (82 per cent), the NBT reduction capacity was higher than in any control. Vacuolization of the cytoplasm and/or toxic granulation of the neutrophils were demonstrated more often in patients with high than low NBT reduction capacity. In 49 patients (35 per cent), the bactericidal activity of the neutrophils was lower than in any control. Thirty-eight patients (78 per cent) with impaired bactericidal activity had 25 per cent or more peripheral juvenile neutrophils as compared with only 12 (13 per cent) out of 92 patients with normal activity. Vacuolization of the cytoplasm and/or toxic granulation of the neutrophils were demonstrated in 28 patients (57 per cent) in whom the granulocyte function was reduced and in 26 patients (28 per cent) in whom function was normal. Within wide limits, the NBT reduction capacity increased with diminishing bactericidal activity of the neutrophils. Eighteen patients died of infection; 12 had reduced bactericidal activity. Defects in neutrophil granulocyte function caused by bacterial infection may contribute to a fatal outcome of the disease.

The role of immune complexes in the pathogenesis of disease

Circulating antigen-antibody complexes are incriminated in the pathogenesis of auto-immune and inflammatory disease, and more recently malignancy. Extensive knowledge of the immunopathological reactions has evolved from from the study of experimental serum sickness in animals and of the potential aetiological agents (e.g. viruses) from spontaneous immune complex diseases in animals. Numerous techniques, both direct and indirect, have now been described to identify immune complexes in serum, though no single technique will identify regularly immune complexes in all clinical situations, nor will it demonstrate the pathogenicity of the immune complex in a given patient. Human disorders with a definite immune complex basis (glomerulonephritis, systemic lupus erythematosus, rheumatoid arthritis) and others with a possible immune complex basis (e.g. cutaneous vasculitis, are presented. Management of immune complex disorders is based on removal of the initiating agent if known (e.g. infection, drug, malignancy) or the use of non-specific anti-inflammatory therapy. Specific immunotherapy, in practice and theory, is discussed.

Immunoglobulin and complement bearing polymorphonuclear leukocytes in allergic contact dermatitis and psoriasis vulgaris

Immunofluorescence techniques were used to demonstrate the presence of immunoglobulin (Ig) and complement (C) bearing polymorphonuclear leukocytes (PMNL) in specimens of skin from the lesions of ten patients with allergic contact dermatitis and of ten with psoriasis vulgaris. The distribution patterns of these Ig- and C-coated cells in the peripheral blood of the twenty patients were also studied. Ten normal healthy controls were included. In cases of allergic contact dermatitis, IgD was the predominant class of Ig on the PMNL. The percentage of C-bearing PMNL were also significantly increased, suggesting that both molecules might be present on the cell memebrane of these cells at the same time. In psoriasis vulgaris, the predominant class of Ig on the PMNL was IgG. The percentage of PMNL coated with C were not signficantly raised. These results suggest that in allergic contact dermatitis the PMNL can be coated with both Ig and C which may render them cytophilic; they also show that in psoriasis vulgaris PMNL can bind Ig. In the ten healthy controls, it was possible to distinguish between those PMNL which are and those which are not bearing immunoglobulin.