Neuraminidase-mediated augmentation of in vitro immune response of patients with solid tumors

Host blood lymphocytes undergo accentuated blastic transformation when cultured with tumor cells pretreated with neuraminidase. The effect has been observed in 38 patients with such common solid tumors as bronchus carcinoma, skin melanoma, hypernephroma, or adenocarcinoma of the breast, lung, colon, or rectum. Individual response varied but often exceeded response to allogeneic cells. Three patients with glioblastoma of the brain did not respond. Lymphoblastic transformation was not observed in three of four cultures containing benign tumor or in any cultures containing normal tissue analogues of the malignant tumors. A factor in host blood serum inhibiting lymphoblastic transformation correlated to abnormal elevation of serum-bound sialic acid. This blocking factor differed in specificity from enhancing antibody or serum blocking complexes described by other investigators. Blocking effects were observed when the tumor-cell type of a serum donor differed from the cell type of the culture test tumor. Serum with abnormal elevation of bound sialate from a cancerfree human also non-specifically blocked host response to tumor. The blocking effect could be eliminated by partial enzymatic removal of bound sialic acid from serum glycoproteins.