Canine radiation chimeras: an attempt to demonstrate serum blocking factors by an in vivo approach.

An attempt was made to demonstrate in vivo the presence of blocking factors in the serum of canine chimeras with grafts of chimeric skin onto the marrow donor as an indicator system. Even very large amounts of chimeric serum (one-fourth of the plasma volume infused daily from day 2 before skin grafting until rejection) failed to modify first and third set skin graft rejection patterns. Thus, serum blocking factors could not be demonstrated by this in vivo approach.