Overall, positive FCXM reactions were associated with graft losses in regrafts but not in primary transplants. 2. In transplants involving older female or CVA donors, a positive FCXM appeared to be deleterious in both first transplants and regrafts. If the donor were a younger male and not a CVA victim, only FCXM positive regrafts had low graft survival rates. 3. We presented a 3-color technique allowing the differentiation of antibody reactions against T cells, B cells, and monocytes. Another method allows the simultaneous evaluation of both IgG and IgM reactions against T cells. Using these kinds of methods may make better identification of antibodies that may be harmful to a transplant allograft possible.