Serum blocking factors in human recipients of renal allografts

The host response of human renal allograft recipients was studied using the cell inhibition assay. Cellular immunity was present in the majority of recipients early in the post-transplant period, falling to a low incidence in later periods. Conversely, cellular immunity with a blocking effect or nonimmunity was most common late in the posttransplant period. The lack of immunity or the presence of blocking activity correlated well with a good clinical course. Sequential data on six patients support the importance of these factors.