T-CELL TUMORS OF DISPARATE PHENOTYPE IN MICE TRANSGENIC FOR RBTN-2

RBTN2 is a LIM domain protein which can be activated by the translocat ion t(11;14)(p13;q11) in childhood T cell acute leukaemia. Transgenic mice were examined in which rbtn2 protein is expressed in the T cell l ineage. An average of 72% of these mice developed T cell tumours befor e 18 months of age, compared with 9% in transgenic mice expressing the related gene Rbtn-1. Rbtn2-induced tumours first appeared at 5 months of age and were clonal. They displayed a range of phenotypes, the mos t notable being CD3/CD45R double-positive cells. Tumours expressing ei ther T cell receptor alpha/beta or gamma/delta heterodimers were found . Thus rbtn2 can promote tumours within a range of T cell types and ma turities. The latency period before tumour development indicates that secondary events must occur before the onset of overt malignancy.