Background: Giant cell arteritis (GCA) is a vasculitis of medium-size and large arteries which mainly affects old women.
Aims: To elucidate the etiology and pathogenesis of GCA.
Specific questions: a. Which are the characteristics of the inflammatory reaction? b. The inflammation is preceeded by calcification and smooth-muscle atrophy in the arterial wall. Which pathogenetic role do these changes play? Are they caused by programmed cell death or hampered cell division? c. Is GCA associated with a disturbance in estrogen metabolism? d. Does viral infection play a pathogenetic role?
Methods: a. Immunohistochemistry. b. Immunohistochemistry, electron microscopy. c. Immunohistochemistry, RT-PCR, nucleotide sequence analysis, epidemiology. d. Epidemiology, immunohistochemistry, PCR, in situ hybridisation.
Results: The inflammatory reaction starts as a foreign-body giant cell reaction directed at calcifications in the inner layers of the artery (the internal elastic membrane). In the general population, these calcifications increase with age and are more common among women. Their age and sex distribution is thus similar to that of GCA.
Importance: Increased knowledge of GCA is a prerequisite for future optimal diagnosis, treatment and prevention of GCA.