title: Cross-reacting antibodies to Micropolyspora faeni in Mycoplasma pneumoniae infection.
abstract: Two cases are described of severe Mycoplasma pneumoniae infection in whom cross-reacting antibodies developed to a glycopeptide antigen of Micropolyspora faeni. The antibodies were predominantly IgG, although some IgM was detected. Precipitin responses to M. faeni were detected for 4 months after the initial illness in one case, and 1 month in the second case. The cross-reacting antibodies were closely related to the antibodies responsible for the complement fixation reaction to M. pneumoniae. It is suggested that a common polysaccharide antigen may exist on the surface membranes of M. pneumoniae and M. faeni. Initial studies of the frequency of the development of cross-reacting antibodies in M. pneumoniae infection suggest it is uncommon. Atypical cases of farmer's lung should be investigated to exclude M. pneumoniae infection.
mesh_terms: D000042:Absorption; D000192:Actinomycetales / Q000276:immunology*; D000193:Actinomycetales Infections / Q000276:immunology*; D000328:Adult; D000373:Agglutinins / Q000032:analysis; D000907:Antibodies, Bacterial; D000908:Antibodies, Fungal; D000946:Antigens, Fungal; D003080:Cold Temperature; D003168:Complement Fixation Tests; D003429:Cross Reactions; D003450:Cryoglobulins / Q000032:analysis; D005260:Female; D006020:Glycopeptides; D006801:Humans; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D009175:Mycoplasma Infections / Q000188:drug therapy / Q000276:immunology*; D011859:Radiography; D012129:Respiratory Function Tests; D012882:Skin Tests; D013752:Tetracycline / Q000627:therapeutic use
chemical_list: D000373:Agglutinins; D000907:Antibodies, Bacterial; D000908:Antibodies, Fungal; D000946:Antigens, Fungal; D003450:Cryoglobulins; D006020:Glycopeptides; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D013752:Tetracycline