These results indicate that, although the specificity of beta-lactam-specific IgE measurement is good, sensitivity is low. Immunoglobulin E measurement should be limited to patients with a clinical history of anaphylactic shock and negative skin tests in order to avoid a drug provocation test. More sensitive assays should be developed.
A B S T R A C T Alveolar macrophages from nonatopic donors were passively sensitized with allergen-specific IgE antibody from the serum of asthmatic patients. A selective release of 4-8% of the lysosomal fl-glucuronidase of these cells occured within 30 min of contact with the related allergen or with anti-human IgE antibody, in the absence of any mast or basophil cells. The cell reactivity was dependent on the interaction of macrophages with IgE, as shown by the disappearance of the allergen-induced enzyme release after heating or IgE-immune adsorption of the sensitizing serum, but not after IgG-adsorption. Alveolar macrophages from asthmatic patients behaved similarly to passively sensitized normal macrophages. Contact with the related allergen or with anti-IgE antibody induced the same percentage of enzyme release, demonstrating that these cells possess allergen-specific IgE bound on their surface. 18% of them formed rosettes with anti-IgE-coated sheep erythrocytes, and 15-22% with allergen-coated erythrocytes, but lost this property after preincubation with the specific allergen. The presence of IgE-specific receptors on the macrophage surface was demonstrated both at the ultrastructural level with immunoperoxidase labeling, and at low magnification by the formation of 15-18% rosettes with human IgE-coated erythrocytes. The formation of such rosettes was inhibited after incubation of alveolar phagocytes with aggregated myeloma IgE. On
Platelet-activating factor (PAF-acether) was recovered from rabbit, rat and human alveolar macrophages stimulated with the Ca++ ionophore A23187. PAF-acether release was also obtained from rat and rabbit macrophages in the presence of zymosan, but not from human alveolar preparations in spite of the phagocytic activity exhibited by the latter cells. Observed releases were active, Ca++ dependent, and plateaued at 45 min. No PAF-acether was released from lungs washed out of their macrophages, another argument against the mastocyte origin of this mediator. Given the potent bronchoconstrictive activity of PAF-acether, its release from alveolar macrophages may provide an alternative explanation for non IgE-dependent asthmas and the implication of platelets in pulmonary diseases.
Intratracheal administration of platelet-activating factor (paf-acether) induced transient bronchoconstriction in baboons. Using an automated isotopic monitoring system, we found that intratracheal administration of paf-acether also elicited transient accumulation of platelets labeled with 111In oxine within the pulmonary vasculature after the increase in maximal peak inspiratory pressure. Bronchoalveolar eosinophilia were inhibited by prophylactic administration of the antiasthma drug ketotifen but not by pyribenzamine, suggesting that the effects of ketotifen are unrelated to H-1 receptor antagonism. Platelet accumulation was not affected by ketotifen or pyribenzamine. This study suggests that paf-acether may be a mediator of the eosinophil recruitment in bronchial asthma and that inhibition of this phenomenon by ketotifen may contribute to the therapeutic efficacy of this drug.
Depending on the time course of the reaction, three clinical groups were identified: anaphylaxis and anaphylactic shock (immediate reaction); maculopapular exanthema (late reaction) as well as urticaria (immediate and late reaction).
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