IgE myeloma: total body tumor cell number and synthesis of IgE and DNA.

Studies of myeloma cell DNA and immunoglobulin synthesis and total body tumor cell number were performed on a patient with IgE multiple myeloma and plasma cell leukemia; results were contrasted to similar observations in patients with IgG myeloma. Autoradiographic studies demonstrated significantly greater DNA labeling in the IgE patient’s bone marrow plasma cells than in cells from IgG myeloma patients who did not have leukemic manifestations; an additional patient with plasma cell leukemia also had a high labeling index of the myeloma cells in the blood. The IgE myeloma patient’s molecular synthesis rate for immunoglobulin averaged 26,000 molecules of IgE per minute per myeloma cell, a synthetic rate similar to that found in IgG myeloma. These observations have relevance to the normal immune response, as they can be used to approximate the number of normal IgEand IgG-producing cells in the body. In the patient with IgE myeloma, the total body myeloma cell number was 2.7 X 1012 cells at the time of study and was of the same order of magnitude as in IgG myeloma; however, the distribution of tumor cells was strikingly different. Serial estimates of tumor cell number were made; such estimates may prove useful in evaluation and treatment of patients with multiple myeloma. M ULTIPLE MYELOMA is a malignant disorder of antibody-producing cells in which a monoclonal immunoglobulin (NI-component ) is secreted as a tumor product. The incidence of myeloma of different imnsunoglobulin classes approximates a ratio to the normal serum concentrations1 of IgG, IgA, IgD, and IgE. IgE, which carries reaginic antibody specificity,2 is the most recently discovered immunoglobulin; it is present in the lowest concentration in normal senim. M-components of the IgE class accompany the rarest type of myeloma recognized thus far; only two cases involving IgE clones have been described.4’5 Interestingly, both patients had plasma cell leukemia, although this generally is a rare manifestation of myeloma.