Structural studies on an IgM-lambda pyroglobulin.

An IgM-lambda pyroglobulin from a patient with Waldenström's syndrome was studied. Heavy and light chains were separated and their N-terminal amino acid sequence determined. The heavy chain was unblocked and belonged to the VHIII subclass, and the light chain belonged to the lambda I subclass. Factors influencing pyroprecipitability were examined through experiments designed to study some of the physical and chemical properties of an IgM-lambda pyroglobulin. Pyroprecipitability was affected by pH, ionic strength, urea, and reducing agents, suggesting an involvement of noncovalent electrostatic interactions. It was also demonstrated through recombinant experiments that it is necessary to have covalently joined homologous heavy and light chains in pentameric form for pyroprecipitation to occur. Since neither heavy nor light chains had any unique structural features, the reasons for this property remain obscure but may reflect the result of conformational factors.

IgD-plasma cell leukemia associated with pyroglobulinemia and pyroglobulinuria. New types of pyroglobulin and cytoplasmic fibrils.

New pyroglobulin variants were found in a patient with a typical plasma cell leukemia. One was found in the urine and proved to be a variant of Bence-Jones' protein with a molecular weight of approximately 68,000. The other was found in the serum and appears to be the myeloma protein of IgD. Furthermore, an ultrastructural study disclosed myeloma cells in both peripheral blood and bone marrow to have cytoplasmic fibrils which might be unique for plasma cell leukemia.

Further characterization of milk pyroglobulin.

Milk pyroglobulin was capable of passing through the "Visking" 8/32 cellulose membrane, when dialysed against deionized water but not against saline. Gel filtration analysis of the protein suggested its dissociation into subunit molecules in deionized water. Amino acid composition revealed high contents of proline, glutamic acid, valine and leucine. The protein possessed a biological activity to increase the permeability of skin vessels when injected intradermally. The colostral whey which was experimentally freed from heat-coagulable substances contained as major components proteins which are antigenically related to the pyroglobulin.

A new protein with a particular thermoprecipitability in bovine milk.

A new protein with a particular thermoprecipitability was isolated from bovine milk and tentatively termed milk pyroglobulin. The protein which was soluble at a relatively cold temperature was precipitated by raising the temperature to a certain degree depending on the concentration of the protein. The precipitate disappeared on recooling. This protein had the electrophoretic mobility of gamma globulin but did not carry either antigenic specificities of immunoglobulins or of free secretory component. The molecular weight was estimated to be approximately 60,000 in thin-layer gel filtration on Sephadex G-200 superfine gel, but the protein appeared to be convertible to molecules with a lower molecular weight of approximately 20,000 in the presence of bovine serum albumin. The presence of the albumin inhibited the thermoprecipitation as did alpha-lactalbumin but not IgG immunoglobulin from bovine colostrum. In SDS-polyacrylamide gel electrophoresis, the protein was separated into two components having a molecular weight of 19,000 and 10,000, respectively. Both components were thermoprecipitable and carried identical antigenic determinants.