Abstract: The invention relates to a method for in-vitro detecting pathogenic T helper cells by incubating a sample of a body fluid or tissue taken from a mammal with substances specifically interacting with at least one gene product encoded by selected genes, which are differentially expressed compared to normal T helper cells, determining specific incubation products, correlating an amount of signal or change in signal with a concentration of the gene product in the sample, and detecting cell pathogenicity by comparing the concentration with another gene product concentration in a sample of non-pathogenic and/or pathogenic cells. Another object if the invention concerns a pharmaceutical composition for prophylaxis and therapy of chronicinflammatory. The invention also relates to a method for screening substances with the property to reduce the pathogenicity of T helper cells along with the symptoms of chronic inflammatory diseases.