Prolonged survival of skin grafts in mice following treatment of the donors with fractions of cell-free Ehrlich ascites fluid

The aim of the present study was to characterize the factor in Ehrlich ascites tumor (EAT) which, upon injection to graft donors, leads to prolonged graft survival in allogeneic recipients. Donors of skin grafts were injected with cell free Ehrlich ascites fluid (CFEAF), with various fractions of the fluid, or with saline. Allografts from CFEAF-treated donors showed a significantly prolonged survival. A similar effect was obtained with male to female grafts within the C57BL strain. The activity of CFEAF was maintained upon freezing at - 18°C for several days. Ultra centrifugation of CFEAF to remove any possible virus particles did not reduce its capacity to prolong skin allograft survival. Thus the activity of CFEAF could not be attributed to the presence of either viable tumor cells or virus particles. Treatment of donors with either sediment or supernate obtained by precipitation of CFEAF with 33% ammonium sulfate allowed some of the male to female isografts to survive permanently. Fractionation of CFEAF on a DEAE-cellulose column gave a fraction which upon injection to skin allograft donors caused a highly significant prolongation of skin graft survival. This fraction gave three precipitation lines with antiwhole mouse serum. One of the proteins in the fraction was identified as IgM and it is possible, therefore, that gamma globulin may be the active factor in CFEAF.