IRTA1 and IRTA2, novel immunoglobulin superfamily receptors expressed in Bcells and involved in chromosome 1q21 abnormalities in B cell malignancy

Abnormalities of chromosome 1q21 are common in B cell malignancies, but the ir target genes are largely unknown. By cloning the breakpoints of a (1;14) (q21;q32) chromosomal translocation in a myeloma cell line, we have identi fied two novel genes, IRTA1 and IRTA2, encoding cell surface receptors homo logous to the Fc and inhibitory receptor families. Both genes are selective ly expressed in mature B cells: IRTA1 in marginal zone B cells and IRTA2 in centrocytes, marginal zone B cells, and immunoblasts. As a result of the t (1;14), IRTA1 is fused to the immunoglobulin C alpha domain to produce a ch imeric IRTA1/C alpha fusion protein. In tumor cell lines with 1q21 abnormal ities, IRTA2 expression is deregulated. Thus, IRTA1 and IRTA2 are novel imm unoreceptors implicated in B cell development and lymphomagenesis.