Fluorometric determinations of the relative immunoglobulin content of plasma cells of patients with monoclonal gammopathy.

The relative cytoplasmic immunoglobulin content of fixed plasma cells taken from the bone marrow of five patients with myeloma and five patients with benign monoclonal gammopathy was determined with a microscope fluorometer. In eight of the ten piasma cell populations studied, the distribution of the fluorescence intensities was close to normal. In three of these eight populations a significant difference in the variances of the heavy and light chain fluorescence intensities was found. Variances of heavy and light chain fluorescence intensities were smaller in patients with an immunoglobulin A-type gammopathy than in those with an immunoglobulin G-type gammopathy. No difference was found if normalized relative frequency distribution patterns of heavy or light chain fluorescence intensities of patients with myeloma were compared with those of patients with benign monoclonal gammopathies.