[Allergy to radiographic contrast media]. / Allergies aux produits de contraste radiologiques.

Allergy to radiographic contrast media Hypersensitivity reactions to radio-contrast media are common in the daily practice. These products are responsible for immediate (< or = 1 hour after administration) and non immediate (> 1 hour after administration) hypersensitivity reactions. A diagnostic work-up by an allergologist with skin tests and in some cases provocation tests is of value in reducing the risk of recurrent hypersensitivity reactions to iodinated contrast media. A careful selection of the patients is required because the incidence of breakthrough reactions is still concerning, even with proper premedication. Practical recommendations are presented in this article. For gadolinium-based contrast agents, data in the literature is not sufficient for suggesting guidelines.

[Use of autoantibodies in clinical practice]. / Utilité de la recherche des autoanticorps dans la pratique quotidienne.

Autoantibodies are frequently determined in unclear clinical situations and in the context of an inflammatory syndrome. The aim of this article is not to review all autoantibodies in details, but to discuss those used in clinical practice by describing their methods of detection and interpretation. Thus we will focus on antinuclear antibodies (ANA), which are typically associated with connective tissue diseases, as well as anti-neutrophil cytoplasmic antibodies (ANCA), which are useful in the diagnosis of ANCA-associated vasculitides. Due to its high sensitivity indirect immunofluorescence is used as a screening test; when positive, ELISA is performed to search for antibodies more specifically associated with certain auto-immune diseases.

[Large vessel vasculitis: giant cell arteritis and Takayasu arteritis]. / Les artérites des grands vaisseaux: maladie de Horton et maladie de Takayasu.

Giant cell arteritis (GCA) and Takayasu arteritis (TA) are both chronic granulomatous vasculitis of unknown aetiology that involve large vessels. Signs and symptoms are related to the affected vessels: the primary branches of the aorta in TA and the extra-cranial branches of the external carotid artery in GCA. TA affects women under 40 of all ethnic origins with a greater prevalence in Asia, whereas GCA affects elderly of caucasian ancestry. In both diseases the diagnosis and follow up are rendered difficult by the absence of specific marker but advances in imaging technologies such as angio-MRI and PET/CT are very promising. Corticosteroids still represent the basis of treatment, most often alone in GCA and usually in association with another immunosuppressive drug in TA.

Skewed representation of functionally distinct populations of virus-specific CD4 T cells in HIV-1-infected subjects with progressive disease: changes after antiretroviral therapy.

HIV-1- and cytomegalovirus (CMV)-specific CD4 T-cell-mediated antiviral immunity was evaluated by assessing the frequency of interleukin 2 (IL-2)- and interferon gamma (IFN-gamma)-secreting cells following antigen-specific stimulation in blood and lymph node. HIV-1-infected subjects with progressive disease at early stage of infection with no previous history of antiretroviral therapy (ART), subjects with nonprogressive disease, and HIV-negative subjects were studied. On the basis of the ability to secrete IL-2 and IFN-gamma, 3 functionally distinct populations of CD4 T cells were identified: (1) IL-2-secreting cells; (2) IL-2/IFN-gamma-secreting cells; and (3) IFN-gamma-secreting cells. CMV-specific CD4 T cells were almost equally distributed within the 3 functionally distinct cell populations in the 3 study groups as well as HIV-1-specific CD4 T cells in subjects with nonprogressive disease. However, a skewing toward IFN-gamma-secreting cells (70% of HIV-1-specific CD4 T cells) was observed in subjects with progressive disease, and IL-2- and IL-2/IFN-gamma-secreting cells were almost absent. The frequencies of IL-2- and of IL-2/IFN-gamma-secreting HIV-1-specific CD4 T cells were negatively correlated with the levels of viremia. Interestingly, prolonged ART was able to correct the skewed representation of different populations of HIV-1-specific CD4 T cells but was associated with only a partial recovery of IL-2-secreting cells. These results indicate that the composition of the pool of functionally distinct virus-specific CD4 T cells is important for virus control.