Sialic Acid on Leukemia Cells: Relation to Morphology and Tumor Immunity

Blast cells from 35 patients with adult acute leukemia and mononuclear cells from 10 normal donors were treated with neuraminidase and the amount of sialic acid released was measured. These values were correlated with the ability of the unmodified blasts to stimulate blastogenesis among autologous remission lymphocytes. Uniformly low amounts of sialic acid were released from leukemia lymphoblasts (10 patients). This was correlated with a consistently poor ability of these lymphoblasts to stimulate autologous lymphocytes. In contrast, a wider range of sialic acid levels were determined for leukemic myeloblasts (25 patients). Myeloblasts releasing excessively high amounts of sialic acid tended to stimulate autologous lymphocytes poorly compared to the vigorous stimulation evoked by myeloblasts releasing lower amounts. Similar studies of cell surface properties should facilitate the understanding of the immune response evoked by human tumor cells. We thank Dr. E. Wolberg, Jr., from the Department of Biochemistry of The University of Texas at Houston, M. D. Anderson Hospital and Tumor Institute, Houston, Texas, for his advice and Mrs. Carol Hunter for technical assistance.