Natural cytotoxicity of human serum. A natural IgM 'antibody' sensitizes transformed murine cells to the lytic action of complement

The cytolysis of human neuroblastoma cells by a natural IgM 'antibody'-complement system in pregnancy serum

Cell lines from 26 human cancers were studied for cytotoxicity when treated with normal pregnancy serum. Cytotoxicity manifested by cell death and cytolysis, occurred in 4 of 8 neuroblastomas studied: SK-N-SH, NGP, LAN-5, and IMR-32. In NGP and SK-N-SH, evidence is presented showing that the cytotoxicity resulted from the cell-surface binding of a natural IgM 'antibody', which sensitized the neuroblastoma cells to the lytic action of complement (C). This system may be involved in a cytolytic form of spontaneous regression of neuroblastoma.

Spontaneous regression of neuroblastoma: an experimental approach

The cytolytic activity of normal pregnancy serum was first studied on murine cancer cells and shown to be the result of a natural IgM antibody that binds to cell surfaces and activates complement. Both the classical and alternative pathways of complement are involved. It was then shown that certain human neuroblastoma cell lines, to the exclusion of other human cancers, react to the same system. It is proposed that this system may play a role in the cytolytic form of spontaneous regression of neuroblastoma.