A monoclonal IgM lambda macroglobulin with specificity for lacto-N-tetraose in a patient with bronchogenic carcinoma

The serum of a patient with bronchogenic carcinoma was found to contain a monoclonal IgM lambda (IgMwoo) that precipitated with a precursor blood group glycoprotein containing I and i determinants. IgMwoo did not agglutinate O cells in the cold or at room temperature, and by quantitative precipitin and precipitin inhibition assay its specificity was shown not to be to the I and i determinants. IgMwoo reacted best with lacto-N-tetraose, DGal beta 1 leads to 3DGlcNAc beta 1 leads to 3DGal beta 1 leads to 4DGlc, and was specific for the non-I or non-i determinant dGal beta 1 leads to 3DGlcNAc beta 1 leads to 3DGal-moiety present as a distinct chain on precursor glycoproteins containing I and i determinants. Human ovarian cyst blood group A and B glycoproteins were inactive, but removal of the outer tier of sugars involved in A, B, and H specificity exposed this non-I or non-i determinant as well as the determinant reacting with anti-I Ma. IgMwoo was neither a cold agglutinin nor a cryoglobulin. It precipitated with precursor blood group glycoproteins somewhat less at 37 degrees C than at 0 degrees C, the differences being ascribable to solubility.