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Notes: Fractions with affinity for heat-denatured human IgG (HDG) were isolated from four sera that contained intermediate complexes (IC). These IC fractions contained part of the 7S IgG, all IC, and part of the rapidly sedimenting complexes (RC) found in the sera. The IC consisted of IgG1 or IgG3 and the RC of IgG and IgM with kappa and lambda light chains. The IgG in the IC fractions contained an abnormally large amount of neuraminic acid. No correlation between IgG subclass or content of neuraminic acid and complex formation was found. There were indications that the formation of IC was not only the result of a self-association of IgG molecules with anti-γ-globulin activity. Specific rabbit antisera were prepared against two of the IC fractions. Affinity chromatography with immobilized IgG and F(ab')2γ from these antisera confirmed the presence of common antigenic determinants in the sera. These determinants occurred mainly in 7S components in one individual, in IC in one and in RC in another. Only a minor part of the serum components with affinity for HDG contained the determinants. RF activity was found in the components that lacked and in those that contained the common antigenic determinants.

Notes: The effect of isolated IgM fractions, with or without rheumatoid factor (RF) activity, on reactions between human albumin and rabbit anti-human albumin, human IgG and rabbit anti-human IgG, and tetanus toxoid and human anti-tetanus toxoid was assessed in the antigen excess zone. RF-active fractions increased and RF-negative IgM fractions decreased the amount of free antigen. The immune complexes that were affected by RF IgM fractions differed in composition from those affected by normal IgM fractions.

Notes: In this investigation, the modulating effects of non-immune human IgG and rheumatoid factors (RFs) on antigen-antibody complexations were studied. Non-immune human IgG, as well as RF, were found to inhibit the binding of antigen to specific antibodies of both human and rabbit origin. In addition, human immunoglobulins were also able to modify the composition of preformed antigen-antibody complexes. The effects were detected by immunological methods in two different antigen-antibody systems (human serum albumin-rabbit anti-HSA and tetanus toxoid-human anti-TT). Changes in biological activities could be followed by employing enzymes (glucose-6-phosphate dehydrogenase and human placental alkaline phosphatase) as antigens. The outcome of the effects was found to be dependent on the ratio of antigen to antibody, the antigen-binding properties of the antibody and its origin, and on the properties of the immunoglobulins added. The observed changes could not be explained only by the presence of specific antibodies in the immunoglobulin preparations. The ability of immunoglobulins to modulate antigen-antibody complexations may provide a rationale for the large amounts of non-specific immunoglobulins in the circulation by preventing premature precipitation and promoting the elimination of antigenic molecules.

Notes: A‘nasal pool’(NP) device, a compressible plastic container with an adapted nozzle, was used to perform a continuous 10-min nasal provocation and lavage. This novel technique brings known concentrations of agents into contact with a large and defined area of the nasal mucosal surface for extended periods of time. Simultaneously, the surface exudations/secretions of the same nasal mucosa are effectively sampled by the NP fluid. A concentration-response study of histamine (80, 400 and 2000 μg/ml) was performed in 12 normal subjects on three different occasions. Exudation of plasma albumin into the lavage fluid was measured to quantitate the histamine-induced airway inflammation. The effect of the dwell time on exudation was examined using histamine (400 μg/ml) instilled in the nasal cavity for time periods from 10 sec to 10 min. The time course of histamine-induced plasma exudation response was studied by exposing the mucosa to histamine (400 μg/ml) for 12 min, with the NP renewed every minute. Allergen-provocations were performed in subjects with hay fever and TAME-esterase activity in the returned lavage fluid was determined to indicate the degree of response. Histamine produced a concentration-dependent increase in albumin levels in the NP fluid; 123·3 ± 25·6, 213·8 ± 19·7 and 430·2 ± 32·0 μg/ml (mean ± s.e.m.), respectively. The time-course study demonstrated that plasma exudation into the lumen occurred promptly and that the exudation response reached a maximum after exposure to histamine for 6–10 min. The dwell-time experiments supported this finding. After 10 min the exudation appeared to decline despite the continued presence of histamine. Allergen provocation resulted in a concentration-dependent increase in TAME-esterase activity of the NP-fluids. It is concluded that the NP technique provides new possibilities in studies of pathophysiology and pharmacology of human airway mucosa. With the NP technique controlled concentrations of mediators, drugs, tracers, etc. can be applied for desirable lengths of time on a well-defined mucosal surface area. This particular area is gently and effectively lavaged during the presence of the NP fluid and when the fluid is recovered by decompressing the NP device.

Notes: Mucosal exudation of almost unfiltered plasma proteins, plasma-derived mediators and fluid has recently been advanced as a major respiratory defence mechanism. Oxymetazoline chloride is a commonly used decongestant agent. By reducing blood flow it may reduce mucosal exudation and thus compromise the mucosal defence capacity. This study examines the effect of topically applied oxymetazoline on histamine-induced plasma exudation into human nasal airways. Twelve normal volunteers participated in a double-blind, randomized, cross-over and placebo-controlled study with pretreatment with a single dose oxymetazoline chloride (5 μg or 50 μg; a dose previously known to reduce nasal mucosal blood flow by almost 50%) prior to the histamine challenge sequence. Nasal lavages were performed every 10 min for 140 min, and three histamine challenges were performed at 30-min intervals during this period. The concentrations of two exudative indices, N-alpha-tosyl-l-arginine methyl ester (TAME)-esterase activity and albumin, were measured in the nasal lavage fluids. Nasal symptoms (sneezing, nasal secretion and blockage) were assessed by a scoring technique.Histamine induced all three symptoms with correlatively raised levels of the biochemical markers for plasma exudation. Oxymetazoline chloride caused a significant decrease in nasal stuffiness, but did not influence the other nasal symptoms or the histamine-induced plasma exudation. It is concluded that histamine-induced plasma exudation is not influenced by topical oxymetazoline. Thus, an important airway defence reaction such as plasma exudation may be little affected by topical α-adrenoreceptor-mediated vasoconstriction. It is further suggested that the antiblockage effect of oxymetazoline can be utilized in nasal research without interfering with the exudative indices which appear on the mucosal surface as a quantitative reflection of the airway tisue involvement in inflammatory processes.

Notes: A great variety of provocations of the airway mucosa produce extravasation of plasma from the abundant subepithelial microvessels. A plasma exudate has important actions through its volume, its specific and unspecific binding proteins, its enzyme systems, and its potent peptides (of kinin. complement, coagulation, fibrinolysis and other systems). If allowed to operate on the surface of an intact mucosa the plasma exudale would have important roles in normal airway defence. Recent observations in guinea-pig tracheo-bronchial airways and in human nasal airways suggest that the mucosal exudation of plasma into the airway lumen is a non-injurious fully reversible process. Threshold exudative responses thus resulted in the appearance of an ‘unfiltered’ plasma exudate not only in the lamina propria but also on the surface of an undisrupted mucosa. Even after extensive luminal entry of exudate the epithelial lining was intact, as judged by light, fluorescence and electron microscopy. Hence, the epithelial barrier was reversibly permeable when approached from beneath by the plasma exudate. This was a distinct increase in outward permeability, because even during the exudation of plasma the mucosa remained a barrier to luminal solutes. It is possible that the exudate itself, by a slight compressive action on the basolateral aspect of epithelial cells, creates intercellular pathways for its entry into the lumen. Contrary to current beliefs, we propose that plasma exudation should be considered a first line respiratory defence mechanism operating together with other systems of the mucosal surface.

Notes: The mucosal plasma exudate with its proteins, enzymes, derived peptides, and matrix molecules is an important factor in inflammatory airway diseases. This study investigated whether topical glucocorticosteroid treatment influences mucosal exudation of bulk plasma (fibrinogen) and the generation of plasma-derived mediators (bradykinins) in seasonal allergic rhinitis. Twenty-two patients with birch-pollen-induced allergic rhinitis participated in a double-blind, randomized, placebo-controlled study during the birch pollen season in 1989. After a 2-week run-in period, the participants received treatment with budesonide (200 μg per nasal cavity and day) or placebo. The patients kept a diary to record their daily nasal symptoms (itching, sneezing, nasal blockage, and secretion). The amount of birch pollen in the air was determined with the aid of a Burkhard pollen trap. A nasal lavage was performed once a week, and the levels of bradykinins and fibrinogen were determined in the lavage fluid samples. The birch pollen season was very mild, resulting in only minor nasal symptoms. In spite of the low pollen exposure, treatment with budesonide reduced the lavage fluid levels of both bradykinins and fibrinogen. The present results show that topical glucocorticosteroid treatment attenuates plasma exudation and the generation of plasma-derived mediators in seasonal allergic rhinitis. This action may not result from simple vascular antipermeability effects of the drug but may rather reflect the anti-inflammatory efficacy of topical glucocorticoids in the airway mucosa.

Notes: Intact rheumatoid factor (RF)-active IgM dissociated soluble antigen-antibody complexes formed in the antigen excess zone, whereas trypsin-digested protein had less effect. The dissociation mechanism involved an interaction between the RF IgM and the Feγ of antibodies in the complexes. RF-active IgM had no demonstrable effect on antigen—antibody complexes when the antigen or the antibody had been immobilized. This was true irrespective of whether the experiments were performed in the antigen or in the antibody excess zone and despite binding between RF IgM and the immobilized proteins.

Notes: Two preparations of human IgG, one acylated withβ-propiolactone (acylated IgG) and one treated at pH 4 with (races of pepsin (pH 4-IgG), were used to study the effect of non-immune IgG on antigen antibody interactions in the antigen excess zone. Employing two immunological methods together with size-exclusion chromatography, we found that the formation of human albumin-rabbit anti-human albumin complexes was inhibited in the presence of human IgG. In addition, IgG seemed to promote the aggregation of already formed complexes. Thus, non-immune IgG may modulate immune complexation by direct molecular interactions. The effect was dependent on the size and composition of the immune complexes as well as on the conformation of the IgG molecules with respect to their shape, isotype, charge, and other surface properties. Some possible mechanisms for the reactions are discussed.