Increase of the in vitro complement-dependent cytotoxicity against autologous invasive human bladder tumor cells by neuraminidase treatment.

Complement-dependent cytotoxicity (CDC) was measured in a 51-Cr release assay against tumor cells from 13 non-invasive and 7 invasive transitional-cell tumors of the urinary bladder. CDC was compared between mechanically dispersed tumor cells and neuraminidase-treated tumor cells. Neuraminidase treatment of bladder tumor cells enhanced their susceptibility to complement-dependent cytolysis. There were no differences in CDC between autologous and allogenic sera. Mechanically dispersed tumor cells showed no significant differences in susceptibility when non-invasive and invasive tumor cells were compared, whereas significant differences in CDC were seen when neuraminidase-treated non-invasive and invasive tumor cells were used as targets. A C2 deficient serum showed significantly reduced cytotoxicity suggesting that the CDC reaction requires classical complement activation. A hypogammaglobulinemic serum showed stronger CDC compared to autologous and other allogenic sera and upon dilution of autologous sera and hypogammaglobulinemic serum CDC declined parallelly.