RESEARCH ARTICLE Gene number determinati

Full list of author information is available at the end of the articleBackground Workshop cluster 1 (WC1) co-receptors belong to group B of the scavenger receptor cysteine-rich (SRCR) super-family, as do CD163, CD5, CD6, and Spα, all of which are expressed in immune system cells [1]. We have shown that WC1 is a member of the CD163 multigene family whose other members are CD163A, CD163b and CD163c-α [2]. WC1 co-receptors are composed of up to eleven extracellular SRCR domains with interdomain homology, organized in the domain pattern of a-[b-c-d-e-d]-[b-c-d-e-d’] according to the nomenclature of Sar-rias et al. [1]. The greatest difference among WC1 genes occurs in the most distal SRCR domain (“a ” pattern) with identities as low as 50%, contrasting with other SRCR domains which have identities of approximately * Correspondence: cbaldwin@vasci.umass.edu1Department of Veterinary and Animal Sciences, University of Massachusetts,and Cynthia L Baldwin1