In vitro adsorption of colon cancer sera over staphylococcus protein A: lymphocyte stimulation by leakage of adsorbance.

Serum factors may be responsible for reduced host-anti-tumor defence. Although there is still confusion about their origin, attempts have been made to immobilize serum components by Protein A columns as a therapeutic modality. In our study the in vitro adsorption of 90% of the IgG from cancer sera on "immobilized protein A" did not influence the inhibitory serum activity as measured in a mixed lymphocyte culture. Therefore, IgG or immune complexes do not seem to be the suppressive serum factor in patients with advanced colorectal carcinoma. There is evidence for leakage of small amounts of protein A from the columns which have immunostimulatory activity. Perhaps this may explain necrosis after a therapeutic immunoadsorption.