Human alpha-fetoprotein: immunosuppressive activity and microheterogeneity.

Purified human alpha-fetoprotein (HAFP) from five patients with hepatoma, one with gastric carcinoma, one with an embryonal cell tumor, and from fetal liver has demonstrated immunosuppressive potencies in vitro which vary over three orders of magnitude. A reversible association of HAFP with the cell surface and a predominant effect on T cells are suggested. No evidence of complex formation between HAFP and mitogen has been found. The microheterogeneity of HAFP has been detailed with crossed immunoelectrophoresis and isoelectric focusing in polyacrylamide gels containing 8M urea, and the immunosuppressive potency of HAFP isolated from a given source can be correlated with the proportion of certain HAFP species contained in it.