 E. A. Carswell

E. A. Carswell is the first-listed author of a 1975 paper describing a host-derived serum activity named tumor necrosis factor. The researchers investigated necrosis in transplanted tumors and distinguished the serum factor's activity from that of residual endotoxin. This supported an indirect route in which a host response could mediate an effect initially associated with the stimulating material.^[ref]

The paper also compared responses in cultured cells: the tested neoplastic cell lines and mouse embryo cultures differed in susceptibility. This is an illuminating experimental distinction between observing a biological effect and identifying its range. It did not establish that every tumor responds, that every other cell is unaffected, or that a therapeutic application follows automatically. A macrophage origin was proposed as an interpretation, rather than directly identified by these experiments.^[ref]