Inhibitory effects of carbohydrates on histamine release and mast cell disruption by dextran

Alloxan diabetic rats failed to show the skin reaction (blue spot) evoked by dextran, whereas the effects produced by histamine and compound 48/80 were not altered. When dextran and glucose were injected simultaneously into the skin the reaction was inhibited. In vitro, mast cell alterations produced by dextran occurred simultaneously with histamine release; both processes were inhibited by glucose, other carbohydrates related to glucose, and inhibitors of anaphylaxis. These experiments suggest that dextran releases histamine by a mechanism similar to that found with 48/80 and anaphylaxis in the rat. The inhibitory effect of carbohydrates may be understood on the basis of a competitive mechanism.

STUDIES ON THE MECHANISMS OF HYPERSENSITIVITY PHENOMENA. IX. HISTAMINE RELEASE FROM HUMAN LEUKOCYTES BY RAGWEED POLLEN ANTIGEN

Human leukocytes, isolated from the blood of ragweed-sensitive donors, release histamine upon reaction with a purified protein antigen derived from this pollen. The release process has been studied with washed cells suspended in a defined, serum-free medium. Physiologic levels of pH, ionic strength, and temperature, as well as both calcium and magnesium, are required for optimal cellular reactivity. The level of cellular sensitivity of approximately 200 ragweed-sensitive donors has been ascertained, and the kinetics of the release process studied. The rate of histamine release is a function of antigen concentration, but even with a large excess of this reagent it is impossible to abolish a lag phase. Chelation of the divalent cations or a decrease in the reaction temperature may be utilized to stop the reaction. These measures are effective both before and after the initiation of histamine release. Diminished cellular reactivity (desensitization) has been achieved by several procedures. These have in common the addition of antigen to cells in an environment deficient in but a single respect, followed by a restoration of optimal conditions. The significance of these data has been discussed and it has been proposed that immunologically induced histamine release is an active, enzymatically mediated process which occurs as a multistep response of viable cells to a specific antigenic stimulus.

ACTIVATION OF A FIBRINOLYTIC SYSTEM IN A DOG WITH MAST CELL TUMOR

Injection of minute amounts 48/80 (35 µg/kg) into a dog possessing widespread mast cell tumors produced an interesting constellation of biochemical and pharmacological responses on the cardiovascular and hematologic systems. Severe cardiac irregularities and an intense lowering of blood pressure occurred. The most obvious changes which occurred on the blood coagulation system were a lowering of the prothrombin consumption and a prolonged increase in the coagulation time. Of paramount importance, however, was the intense fibrinolytic activity which developed in this animal. This phenomenon was also observed in animals not bearing mast cell tumors but occurred only when very high levels of 48/80 (0.75 mg/kg) were administered. Euglobulin fibrinolytic studies suggest that the observed intense fibrinolytic activity may be partially independent of euglobulin system. Heparin, histamine, and protamine in low concentrations did not activate the fibrinolytic system but produced inhibition in high concentrations (10 µg/ml). Canine mast cell tumors contain considerable esterase and proteolytic activity but there was no obvious evidence of their release into the blood after injection of 48/80 along with histamine, but local proteolytic activation in the mast cell tumor occurred.

ANTIGENIC HISTAMINE RELEASE FROM PASSIVELY SENSITIZED HUMAN LEUDOCYTES

With histamine release as an indicator, consistent passive sensitization of normal human leukocytes to specific anligen could be achieved with human serum, fresh or stored at -70 degrees C, from allergic individuals. With certain sera, dilution slowed the rate of sensitization but increased eventual histamine release.

STUDIES ON THE LOCALIZATION OF CIRCULATING ANTIGEN-ANTIBODY COMPLEXES AND OTHER MACROMOLECULES IN VESSELS. II. PATHOGENETIC AND PHARMACODYNAMIC STUDIES

Localization of circulating antigen-antibody complexes in vessels of guinea pigs by means of anaphylactic shock was found to be mediated by histamine that was released at the time of anaphylaxis. The source of the histamine may have been the mast cell as noted in studies employing a direct attack on the mast cells by octylamine. Platelets played apparently little to no role in guinea pigs in the anaphylactic deposition of circulating complexes. Rat anaphylatoxin was found to cause vascular localization and symptoms of anaphylaxis identical with that brought about by antigen-antibody anaphylaxis. This also was found to be dependent upon the release of histamine. Antibody against Forssman antigen in the vessel walls of the guinea pigs also led to deposition of circulating complexes. This was found not to be histamine dependent. The possible role of local increase in vascular permeability in certain experimental disease states in the localization of circulating complexes is discussed.

A COMPARISON OF THE SPECIFICITY OF INHIBITION BY PHOSPHONATE ESTERS OF THE FIRST COMPONENT OF COMPLEMENT AND THE ANTIGEN-INDUCED RELEASE OF HISTAMINE FROM GUINEA PIG LUNG

The ability of a number p-nitrophenylethyl alkyl, phenyl alkyl, chloroalkyl, and aminoalkyl phosphonates to inhibit the activated first component (C'1a) of guinea pig complement, and the antigen-induced release of histamine from sliced, perfused guinea pig lung has been compared. C'1a in its reactivity with these phosphonates is distinctly more similar to trypsin than to any of the other enzymes studied previously. It is suggested that both trypsin and C'1a possess an anionic group in the active center of the respective enzyme, but the distance between the anionic and esteratic site in C'1a might be less than in trypsin. The pattern of inhibition of histamine relase by the alkyl, phenyl alkyl, and chloroalkyl phosphonates is similar to the inhibition of C'1a by these compounds, although distinct differences are apparent. The aminoalkyl phosphonates are distinctly less active inhibitors of histamine release than the corresponding alkyl phosphonates, whereas the reverse is true of the inhibition of C'1a. On the basis of these differences, it is tentatively concluded that the organophosphorus-inhibitable enzymes in the guinea pig systems studied here are similar but not identical.