[Leukotrienes in allergic inflammatory reactions]. / Leukotrijeni u reakcijama alergijske inflamacije.

Production of leukotrienes, lipooxygenase products of arachidonic acid metabolism, plays an important role in inflammatory reactions, particularly well studied in bronchial asthma. Lipooxigenase-5 and lipooxygenase-activating protein-5 are crucial in the production of leukotrienes with potent biological activities. Leukotriene B4 is a leukocytic chemoattractant and it induces aggregation and adherence of leukocytes to endothelial vasculature. Sulfidopeptid leukotrienes (C4, D4 and E4) are potent bronchoconstrictors, producing mucous secretion in the airways and increasing vascular permeability. Leukotrienes participate in the process of inflammation, as well as in early and late asthmatic responses. They are found in the blood, liquid obtained upon bronchoalveolar lavage as well as in the urine, irrespectively whether bronchospasm developed spontaneously or it was induced by an allergen. Administration of the specific leukotriene receptor antagonists or leukotriene synthesis inhibitors ameliorates the symptoms and signs of bronchial asthma.

[The role of prostaglandins in allergic inflammation]. / Uloga prostaglandina u alergijskoj inflamaciji.

Prostaglandins likewise leukotriens are proinflammatory mediators resulting from metabolic degradation of the arachidonic acid originating from membrane phospholipids. The most important products of enzyme cyclooxygenation of arachidonic acid are prostaglandins D2, E2, F2a, tromboxane A2 and prostacyclin. Prostaglandins express their tissue effects via the five basic receptor types. Within the allergic inflammation activated mast cell synthesizes prostaglandin D2 (first lipid mediator) which has bronchoconstrictive and vasodilating effects and attracts neutrophilic leukocytes. Moreover, it also participates in the late phase reactions, six hours subsequent to the exposure to the allergen. This mediator is also important in pathogenesis of urticaria, allergic rhinitis and allergic bronchial asthma. In addition to prostaglandin D2, prostaglandin F2a and tromboxane A2 also have bronchoconstrictive actions, while prostacyclin and prostaglandin E have bronchodilating effects. Inhalation of prostaglandin E prevents asthmatic attacks caused by allergens, strain, metabisulfite and ameliorates attacks of aspirin asthma, which confirms the hypothesis that aspirin asthma is based on cyclooxigenase inhibition and increased leukotriene production. In patients with atopic dermatitis, prostaglandin E has suppressive effects on Interferon gamma production by Th1 helper cells and increases production of Interleukin 4 by the Th2 cells. Tromboxane A2 plays a certain role in the development of bronchial hyperreactivity and late asthmatic response. Prostaglandins are also important mediators in the pathogenesis of allergic conjunctivitis. Most of nonsteroidal antiinflammatory drugs inhibit the enzyme cyclooxygenase and thus also prostaglandin biosynthesis and release.

[The role of thrombocytes in allergic inflammation]. / Uloga trombocita u alergijskoj inflamaciji.

The platelet has traditionally been associated with haemostasis. Participation of platelets in defence mechanisms is presentiment by the knowledge that primary haemostasis may be phylogenetic vestige retained from the behaviour of primitive leukocytes. Platelets have the ability to undergo shape change with pseudopod formation, chemotaxis, diapedesis, and phagocytose. Platelets contain a wide range highly potent inflammatory factors that are capable of inducing or augmenting certain inflammatory responses. Different surface molecules have been detected on the plasma membrane, highlight the platelets ability to bind a variety of biologic surfaces, including those of other cells, resulting in close apposition of platelets and their targets. They can interact with parasites, viruses and bacteria. Studies from several groups suggest an important role of the platelet in allergic processes. Platelets possess receptor for immunoglobulin E. Numerous clinical reports are describing the modification of biologic activity of platelets from allergic patients as compared to healthy subjects. The incidence of abnormal platelet responsiveness is in higher among patients having high serum IgE titres. Platelet depletion decreased the anaphylactic response and protects against the lethal consequences of the antigen provocation. Evidence now exists in support of primary role of the platelet in the pathogenesis of bronchial asthma. Platelets can participate in allergic asthma by acting as inflammatory cells, by releasing spasmogens and by interacting with other inflammatory cells. Thrombocytopenia and the increased plasma levels of platelet-derived markers occurred in parallel with bronchoconstriction induced by antigen provocation of allergic astmatics. Platelet depletion inhibits the ability of antigen to induce late onset airways obstruction and airway hyperresponsiveness. Platelet apheresis in human resulted in a positive clinical effect. Platelets respond to aspirin or other NSAIDs in acetyl salicylic acid sensitive asthmatics and these findings provide further evidence for role of the platelet in this form of bronchial asthma.

[Sjogren's syndrome]. / Segrenov sindrom.

Sjogren's syndrome is a chronic inflammatory disease of unknown aethiology. It is characterized by decreased secretion of salivary and lacrimal glands, which induces keratoconjunctivitis sicca and xerostomia. Sjogren's syndrome is a central autoimmune disease, and it has characteristics of both organ-specific and generalized autoimmune diseases. It can exist as a primary disease or is associated with other autoimmune diseases (most freyuently with systemic lupus erythematosus or rheumatoid arthritis) and is classified as a secondary Sjogren's syndrome. The aethiology is multifactorial, and it has not yet been completely explained. In the pathogenesis of the disease the important role have genetic predisposition, chronic oestrogen stimulation, end viral infections, especially of the herpes virus group (EBV, CMV, HHV6) and retroviruses. In the clinical picture xerostomia, xerophtalmia and non-erosive arthritis are the most common features, with the whole spectrum of extraglandular manifestations of respiratory, gastrointestinal, skin, and haematologic, neurologic and endocrinologic disturbances. Pathohistological findings of minor labial salivary gland lymphocyte infiltration is the most specific and the most sensitive diagnostic criterion of Sjogren's syndrome. The diagnosis of keratoconjunctivitis sicca is made by Schrimer's test, Rose bengal dye staining and by the "tear break up time". Differential diagnosis of Sjogren's syndrome includes an extremely large number of various pathologic states. The treatment of Sjogren's syndrome consists of symptomatic treatment of dry mucosas (artificial tears, etc.) and also of antiinflammatory drugs, glucocorticoids, immunosuppressive drugs. Plasmapheresis and intravenous administration of immunoglobulins are used for immunosuppression in these patients.