Transmembrane (TMEM)-176A and 176B proteins are closely related to MS4A (membrane-spanning 4-domains subfamily A) proteins []. Their levels are significantly elevated in certain cancers [, ]. TMEM176B (LR8, Torid, Clast1) is broadly expressed, but was up regulated in antigen presenting cells in a rat model of allograft tolerance []. Their role in the immune system is unclear.