Study of the T CD8 Immune Response in Horton's Disease

The research hypothesis is that T lymphocytes CD8 play a role in the physiopathology of Horton's disease. At the inclusion visit, patients will have, as is the case in the usual strategy: * A complete clinical examination carried out by the doctor in charge of the patient * ESR, and CRP and fibrinogen assay * A full blood count for leukocytes and lymphocytes * A biopsy of the temporal artery (TAB) to screen for signs of vascularitis, suggesting Horton's disease. The clinician in charge of the patient will decide if a second biopsy is necessary. The biopsy will be sent to and analysed at Anatomy and Pathological cytology service. Immunohistochemical analyses will be done if the TAB is positive. In addition to the standard clinical examination and complementary examinations relative to the patients' pathology, the following will be done: * Lymphocyte immunophenotyping for the quantity of T CD4 (cluster of differentiation 4) and CD8 lymphocytes, B lymphocytes and natural killer lymphocytes. This will make it possible to calculate the absolute value for different T lymphocyte populations. * A blood sample drawn into a dry 5 mL tube (large yellow) to isolate the serum, which will be stored at -80°C for future assays for cytokines and other biomarkers of interest for Horton's disease. * 16 blood samples drawn into 6 mL heparinized tubes (large green). These will be used immediately for cytometric and functional analyses.