ABSTRACT
Immunofluorescence (IF) studies are important diagnostic tool in understanding pathogenesis involved in graft injury. Acute humoral rejection (AHR) associated with circulating donor-specific cytotoxic antibodies, is a poor prognosticator for graft survival. It can be diagnosed by staining for C4d antibody using indirect IF technique. C4d staining required to diagnose AHR was made mandatory for reporting renal allograft biopsies in 7th Banff conference. We present 2 years experience of IF studies using C4d polyclonal antibody on 546 renal allograft biopsies belonging to two groups of patients; 464 from group A (tolerance induction protocol) and 82 from group B (controls). We observed C4d focal positivity in 4 (0.9%) biopsies from group A and 4 (4.9%) from group B. We conclude that it is advisable to collect simultaneous core biopsy samples for IF studies and light microscopy to give better definition of allograft injury and thereby support in clinical management.