Cancer in ataxia-telangiectasia patients: analysis of factors leading to radiation--induced and spontaneous tumors.

Persons with the genetic, autosomal recessive human disorder ataxia-telangiectasia (A-T) have a predisposition to cancer, though the reason for this is not understood. Studies carried out in recent years have provided evidence that cultured skin fibroblasts from A-T patients are hypersensitive to X-radiation and radiomimetic drugs. These cells were also found to release a clastogenic factor and an angiogenesis-like factor into the conditioned medium. Similar factors present in the plasma of A-T patients may be the cause of chromosomael breakage and blood vessel proliferation respectively. It is suggested to that continual chromosomal breakage in lymphocytes, induced by the clastogenic factor, leads to a selection of T or B lymphocytes with neoplastic properties. Future studies should be directed towards skin Langerhans cells to determine their role in the immune deficiency and their interaction with other cellular elements in the skin of A-T patients. Furthermore, T and B lymphocytes from A-T patients with tumors should be cultivated in vitro to study the nature of the activated oncogenes and the possible role of viruses in blood neoplasms in A-T patients.