Enhanced antigenicity of autologous leukemia cells enriched with cholesterylhemisuccinate

Cholesterylhemisuccinate (CHS) has been used by different authors to enhance the antigenicity of tumor cells in human and in animals. In the present study, leukemic cells isolated mainly from patients with chronic myeloid and chronic lymphocytic leukemia were incubated for 90 min at 37° in PBS containing 3.5% polyvinylpyrrolidone, 0.5% glucose, 1% human serum albumin and 150 μg/ml CHS. 5 x 10⁶ pretreated, irradiated, autologous leukemic cells were tested for their ability to elicit a delayed type hypersensitivity skin reaction. The negative controls included CHS-treated and untreated non-leukemic autologous blood cells as well as substance controls. Recall antigens such as tetanus, diphtheria and tuberculine included in the Multitest Merieux served as positive controls. Results from 28 patients and 44 skin tests are presented. 19 of 23 patients tested under the best of experimental conditions generated a positive skin reaction with the CHS-treated autologous leukemic cells. Less than 12% of the patients reacted with any of the above negative controls. Under the same conditions, more than 90% of the CLL patients were reactive. 5 CLL patients were selected for a treatment including 6 weekly injections of 5 x 10⁶ to 5 x 10⁸ autologous CLL cells. 3 patients experienced an up to 60% reduction of their initial leukocyte counts. In one patient, the leukocyte counts continued to decrease more than 6 months after the treatment was completed. One patient showed no response and in one patient with increasing leukocytes this increase could not be reversed. The results are discussed in terms of earlier observations that membrane sterol content influences the presentation of cell surface proteins.