B cell ontology in a model marsupial

Abstract

Marsupials, such as kangaroos and opossums, are members of a lineage of mammals that last shared a common ancestor with humans and mice ~160 million years ago. Although they share many of the same components of the adaptive immune system of humans and mice, they also have some significant differences. For example, in addition to conventional αβ and γδ T cells is the presence of a third T cell lineage, the γμ T cell. Like humans and mice, marsupials have homologues of the classical MHC class I and II molecules and many of the non-conventional MHCs such as CD1 and MR1, but in addition, opossums have another MHC class I family called the UT family. Like humans and mice, opossums also have FcRN. However, the development of B cells may also differ significantly. B cell development in the opossum is entirely postnatal. For example, opossums lack the VpreB1 and 2 and λ5 surrogate light chains; however, like birds, they have VpreB3. B cell development also occurs at a slower pace in the opossum and the sites of B cell development in marsupials remain largely unknown. To address these differences and unknowns, we will present our results regarding timing and location of B cell development, and the establishment of immuno-competence in a model marsupial, the laboratory opossum Monodelphis domestica. Supported by NSF award IOS-2103367