Contamination of anti-immunoglobulin reagents with antibodies to beta 2-microglobulin and other unrelated antigens. Effects on immunofluorescence staining of human lymphocytes.

IgG fractions from three of four rabbit antisera to Bence Jones proteins of chi-type were found to contain antibodies to beta 2-microglobulin and to stain 80%-100% of human blood lymphocytes by indirect immunofluorescence. Antibody fractions from these sera, which contained anti-beta 2-microglobulin but not anti-Ig, stained all lymphocytes, whereas the isolated anti-Ig antibodies (anti-chi) stained only a minor cell population. In both instances, the specificity of the staining was confirmed by absorption experiments. One antiserum to the constant half of lambda-type Bence Jones protein also contained antibiodies to beta 2-microglobulin and stained all lymphocytes. Four other anti-lambda reagents contained no antibodies to beta 2-microglobulin and stained at most about half of the lymphocytes. The antigen responsible for this staining is unknown. The isolated anti-immunoglobulin antibodies (anti-lambda) stained only 5%-10% of the lymphocytes. Antisera to serum IgG or its fragments were free of antibodies to beta 2-microglobulin and stained only 10%-25% of the lymphocytes. This staining was in all instances due to antibodies to human immunoglobulin. Five of eight undiluted sera from normal rabbits with no detectable antibodies to human immunoglobulin or beta 2-microglobulin stained 25%-60% of the lymphocytes. This staining rapidly disappeared on dilution.