Abstract: The invention relates to a method for diagnosing allergic complaints, atopic diseases and/or auto-immune diseases, according to which a sample from a patient is analysed for the presence of anti-CD28 auto-antibodies by bringing said sample into contact with CD28. If auto-antibodies bond to the CD28, this indicates the presence of an allergic complaint, atopic disease and/or auto-immune disease. The invention also relates to the use of CD28 for diagnosing said diseases and to a kit that is designed for this purpose, comprising CD28 and marked anti-immunoglobulin antibodies.

Abstract: The invention relates particularly to peptides which are specifically capable of binding IgE antibodies and can be obtained from naturally occurring S. aureus enterotoxin B (SEB), for example. The immune-modulating properties thereof are substantially different from those of bacterial SEB. Surprisingly, the inventive peptides do not induce proliferation of T cells, as opposed to SEB. Due to their properties, said peptides are suitable for treating diseases that are characterized by an increased serum IgE level and/or an increased production of interferon gamma and for treating diseases that are characterized by an imbalance in the Th1 and Th2 response, e.g. atopic eczema, lupus erythematosus, Crohn's disease, multiple sclerosis, psoriasis, and rheumatoid arthritis.