Detection of p73 antibodies in patients with various types of cancer: immunological characterization

p53 antibodies have been found in the sera of patients with various types o f cancer. The presence of these antibodies is generally associated with p53 accumulation in the tumour that is believed to trigger this humoral respon se. The recent discovery of 2 new members of the p53 family, p73 and p63, l ed us to study the specificity of this immune response towards the 3 protei ns. Serum samples from 148 patients with various types of cancer were teste d for antibodies against p73 and p63 using immunoprecipitation. 72 patients were previously shown to have p53 antibodies whereas 76 were negative. The control group consisted of 50 blood donors. p73 were detected in 22/148 (1 4.9%) of the cancer patients (11/72 in the group with p53-antibodies and 11 /76 in the negative group). Only two sera from the control (4%) were positi ve, p63 antibodies were detected in only 4/148 (2.7%) of the cancer patient s. Epitope mappings were performed and demonstrate that p73 antibodies are directed toward the central region of the p73 protein whereas p53 antibodie s react predominantly toward the amino- and the carboxy-terminus of p53. Ou r results indicate that there is a specific immune response toward the p73 protein in cancer patients, a finding supported by an increasing number of publications describing p73 accumulation in tumoral cells. (C) 2001 Cancer Research Campaign http://www.bjcancer.com.