Abstract
All mammalian neonates are highly dependent upon milk for nourishment and immune protection. This is especially true for marsupials, a lineage of mammals with limited placental development and an increased reliance on an extended lactation period. Most newborn marsupials do not receive passive maternal immunity in utero and therefore are entirely dependent upon factors within the milk for immune protection until capable of mounting their own responses. Early exposure to potential pathogens, prior to the development of a functional immune system, requires a complex strategy for providing immunological protection. Preliminary transcriptome sequencing results revealed two distinctive peaks in transcription of immune transfer related genes within the mammaries throughout the course of lactation. Additional time points were investigated using quantitative real-time PCR targeting specific immune markers. Lymphocyte markers (CD3E and CD79b) were elevated in a biphasic pattern of expression throughout lactation, suggestive of two waves of lymphocytes entering the mammaries throughout lactation. Immunohistochemistry analyses are underway to investigate the presence of lymphocytes within the mammaries throughout lactation and correlation with gene expression patterns. These investigations have the potential to impact the understanding of the role lactation plays in neonatal immune development from an evolutionary perspective.