Studies on a new acute phase protein. I. Immunocytochemical demonstration of the origin.

Synovial fluid of patients with rheumatoid arthritis or traumatic arthritis contains an antigen which is thermostable to boiling temperature and insoluble in ethanol. The antigen was not found in sera of healthy subjects but it is present in numerous sera of patients with different inflammatory diseases. The partial purification of the antigen and the production of specific antisera are described. Immunofluorescent staining of tissue sections and blood smears indicates, that the antigen is a cytoplasmic protein of polymorphonuclear leucocytes. Monocytes contain the antigen to a lower degree, it was not found in eosinophils and lymphocytes. In addition, the influence of different fixing agents and of other pretreatment on the pattern of the cell fluorescence was studied. We propose to designate the antigen as thermostable granulocyte antigen (TSGA).