Environmental Galactans Which React With IgA Myeloma T191B 1

Six different Balb/c IgA myeloma proteins have been found which bind multiple β-D (16)-linked β-galactopyranose residues. They are J1, S10, X24, X44, J539, and T191B (1). The independent production of different myeloma proteins with the same activity suggests that common natural antigens are present in the environment of the Balb/c mouse and that plasmacytomas may have their origin from precursor cells responding to these natural antigens (2). In fact, it has shown been that S10 and T191B myeloma proteins precipitate with antigenic materials present in food and bedding of mice (3). We now report additional galactans present in the environment of the mouse which precipitate with T191B. One of them, a phosphogalactan from Sporobolomyces sp. consists of approximately equal amounts of α1, 6- and α1, 3-galactosyl linkages (4).

Materials and Methods. Myeloma tumor T191B was obtained from Dr. Michael Potter (National Cancer Institute, Bethesda, MD) and was maintained in Balb/c female mice by subcutaneous passage of tumor fragments. Animals were bled from the ophthalmic plexus after the appearance of a palpable mass and the sera from these animals were pooled.

Quantitative microprecipitin reactions were carried out by adding various concentrations of polysaccharide antigens to 70-μl aliquots of T191B serum and incubating the reactants for 24 hr at 4°C. The N content of the precipitates which formed was determined by Nesslerization (5). Inhibition assays were performed by mixing the inhibiting hapten with T191B serum before the addition of an amount of polysaccharide antigen which gave maximal precipitation.

Screening tests for pollen extracts which would precipitate with T191B serum were carried out by adding 0.025 ml of extract to 0.025 ml of serum, adjusting the volume to 2 ml with isotonic saline, and incubating the mixture at 37°C for 15 min and then overnight at 4°C. In most cases precipitation occurred within minutes.