Pyroglobulinaemia: some characteristics of a heat labile protein.

A case of multiple myeloma with pyroglobulinaemia is reviewed. Certain physical, immunological and chemical characteristics of the pyroglobulin are described. The pyroglobulin precipitate has been shown to bind complement, react with rheumatoid factor, produce passive cutaneous anaphylaxis, generalized passive anaphylaxis and passive Arthus-type reactions. In spite of this experimental demonstration of biological activity of the precipitated pyroglobulin, no clinical abnormality appeared to result from the presence of the myeloma pyroglobulin in the patient.