Mast cell (MC) and peripheral blood basophil (PBB)-associated diseases are treated or prevented, or their symptoms are alleviated by the administration of water soluble fullerenes (buckeyballs) to the individual under conditions sufficient to inhibit MC and PBB responses. MC and PBB responses are associated with, for example, various allergies including Type 1 hypersensitivity initiated by IgE-antigen, arthritis, multiple sclerosis, urticaria, atopic dermatitis, heart disease, etc. The treatment regimen can be enhanced using Chimeric fullerenes that specifically home to and inhibit MC and PBB cells. These molecules, for example, comprise fullerenes to which are attached IgE Fc or stem cell factor (SCF) peptides that bind to receptors specifically on MC and PBB cells. Additional molecules which may be used in the processes include IgE Fc or SCF peptides with several fullerenes covalently attached.