Hypersensitivity to bacteria in eczema

SUMMARY Seven patients with a macroscopic response resembling an Arthus reaction, and occurring 2–4 h after intracutaneous injections of staphylococcal particulate antigens or total staphylococcal extract, were examined for the appropriate specific antibodies that activate complement, and by immunofluores‐cence for antigen, immunoglobulin and complement in the reaction site. Four of the patients had serum antibody, and skin reactions with the typical features of early Arthus reactions and containing immunoglobulin, complement and antigen. Three patients had apparently‘non‐allergic’ responses. They lacked appropriate antibody in serum and immunoglobulin deposits in the lesions, though all except one had complement deposits in reaction sites. One of the three neverthe‐less had histological changes typical of an Arthus response. Lymphocytes teased from the reaction site skin of one patient with a‘non‐allergic’ 4 h response comprised 35 B cells bearing IgG out of 200 counted. The nature of the‘non‐allergic’ response reaching a maximum size at about 4 h macroscopically, and in some instances microscopically resembling an Arthus response, is still to be determined but it illustrates the caution necessary in interpretation of skin tests with bacterial antigens.