In the mutualistic relationship between the squid Euprymna tasmanica and the 
bioluminescent bacterium Vibrio fischeri, several host factors, including 
immune-related proteins, are known to interact and respond specifically and 
exclusively to the presence of the symbiont. In squid and octopus, the white 
body is considered to be an immune organ mainly due to the fact that blood 
cells, or hemocytes, are known to be present in high numbers and in different 
developmental stages. Hence, the white body has been described as the site of 
hematopoiesis in cephalopods. However, to our knowledge, there are no studies 
showing any molecular evidence of such functions. In this study, we performed a 
transcriptomic analysis of white body tissue of the Southern dumpling squid, E. 
tasmanica. Our primary goal was to gain insights into the functions of this 
tissue and to test for the presence of gene transcripts associated with 
hematopoietic and immune processes. Several hematopoiesis genes including CPSF1, 
GATA 2, TFIID, and FGFR2 were found to be expressed in the white body. In 
addition, transcripts associated with immune-related signal transduction 
pathways, such as the toll-like receptor/NF-κβ, and MAPK pathways were also 
found, as well as other immune genes previously identified in E. tasmanica's 
sister species, E. scolopes. This study is the first to analyze an immune organ 
within cephalopods, and to provide gene expression data supporting the white 
body as a hematopoietic tissue.