Revue francaise d'allergologie et d'immunologie clinique最新文献

Mechanisms by which food allergens sensitize atopic individuals still remain unclear. However, most of them are thought to sensitize via the gastrointestinal tract. Due to the very acidic conditions in the stomach and the intense proteolysis occurring in the stomach and in the intestine, only small amounts of intact or immunologically active proteins are taken up by the gut mucosa. This suggested that food allergens are, at least partially, resistant to gastro-duodenal digestion in order to be able to sensitize the mucosal immune system. As a result, several in vitro models have been developed to evaluate the stability of potential allergens to digestion. Indeed, resistance to digestion is part of the premarketing allergenicity assessment of newly expressed proteins in genetically modified crops. However, some food allergens are rapidly and extensively degraded during digestion, whereas some other food proteins that are resistant to digestion are not allergenic. It has been shown that degradation products, i.e. peptide fragments of various sizes, produced during the digestion of a protein may keep (part of) the allergenicity of the native protein. In addition, other factors may interact as to make a food protein an allergen, such as the structure and composition of the food matrix, technologic processing including cooking of the whole food that contains the allergens. Some studies also suggested that the biological property of a protein to be an allergen can influence its mode and route of transport across the intestinal epithelial barrier, which may have a profound impact on the immune responses thus generated. It is noteworthy that a pregastric absorption also occurs, i.e. in the oral cavity, which explains the occurrence of symptoms few minutes after ingestion of food allergens.

The eye imposes limitations on the efficacy and safety of the immune system, which are particularly demanding and contradictory. In contact with the environment, it forms, with its appendages, a small organ which is particularly exposed but apparently not very vulnerable thanks to its various means of defence: a microbial flora similar to that of the skin; blinking of the eyes; the constant flow of lachrymal fluid, whose composition is complex and variable, making it aggressive against microorganisms but protective and nutritive for the cornea, and optically more favourable; and finally, mucosa-associated lymphoid tissue which is characterized by an abundant production of IgA1, IgD and natural antibodies. Both vitreous and a final barrier, the cornea has all the elements necessary for an effective response but as a result of its positioning and its resting state, the eye employs this barrier only as a last resort. The eye is also an optical instrument extending the central nervous system; its vessels must therefore not be connected to the optical axis as any inflammation risks being harmful to the nervous system. This “privileged immunity” is a result of local control of lymphoid cells and immune reactions by molecular exclusion due to hemato-ocular barriers, an inhibitory molecular environment and various cellular interactions that are capable of generating apoptosis and regulatory lymphocytes. In addition, this control can be combined with a systemic response characterized by diminished delayed hypersensitivity, facilitating the production of noncomplement fixing antibodies and the generation of antigen-specific regulatory T cells, a phenomenon called “immune deviation associated with the anterior chamber of the eye”. However, the relative inaccessibility of the immune system to the healthy eye can make the mechanisms of peripheral immune tolerance less effective and lead to a particular vulnerability to autoimmunity and antiretinal autoantibodies in paraneoplastic syndromes. The eye is thus armed to react but its response is closely controlled and oriented; the link between eye diseases and the HLA and the complement systems are also keys to a better understanding of the molecular mechanisms at work there.

Atopic dermatitis has no specific characteristics. It is frequently exacerbated at work. It is important to know the characteristics of the patient's workplace in order to recommend appropriate management (occupational physician, occupational dermatologist).

C1 esterase inhibitor deficiency is an uncommon disorder characterized by recurrent episodes of angioedema without urticaria, abdominal pain attacks, and life-threatening upper airway obstruction. C1 inhibitor is a serine protease inhibitor that inactivates several different proteases in the complement, contact, coagulation, and fibrinolytic systems. Diagnosis requires careful medical and family history and the measurement of antigenic and functional C1 inhibitor and C4 levels. Inherited C1 inhibitor deficiency is usually transmitted as an autosomal dominant trait and detected during the first or second decades of life. More than 200 mutations have been described (deletion, missense mutations, splice site mutations, stop codon mutations).

Hypersensitivity pneumonitis (HP) is a respiratory disease resulting from the inhalation of antigens to which the exposed subject was previously sensitized. HP is characterized by a diffuse and predominantly mononuclear cell inflammation of the alveolar regions that generally involves the small airways. Bronchiolitic lesions are well-described in histopathologic studies. This pathology explains the presence of mosaic attenuation and expiratory air trapping on thoracic scans. Chronic bronchitis with ventilatory obstruction and emphysema as a long-term outcome are possible consequences of this bronchial involvement.

Quaternary ammonium compounds classified as cationic detergents are increasingly used as disinfectants for various purposes. They are classically irritants but can also cause delayed irritant reactions that are sometimes difficult to distinguish from true allergic reactions based on clinical examination and patch testing. Benzalkonium chloride is the quaternary ammonium component now used most extensively medically. As a rule, cross-reactions are observed between different quaternary ammoniums compounds. True allergic responses may be obtained by testing in a 0.1% aqueous solution or in petrolatum.

After three decades of practice in the field of allergy and clinical immunology, the increasing demand of patient care in allergy, together with the increased need for the training of medical generalists and specialists, have led us to develop a continuing medical education program in this field. This 24-month program, which now exists in Algiers, leads to certification in allergy/immunology. Professors from Algerian and foreign universities contribute to it. The majority of the allergy clinics which may be involved do not at present meet all the criteria of accreditation but it is anticipated that these criteria will be met in the coming years due in large part to this introductory program, together with the continuing medical education that has been available in our country since 1990.