Invertebrate immunological memory: could the epigenetic changes play the part of lymphocytes?

Different hypotheses have been suggested for the neurological memory storage in vertebrates, either based on the structural induction of synaptic plasticity or on chemical modifications, i.e., DNA rearrangement. For invertebrates, DNA rearrangements, and in particular the involvement of epigenetic mechanisms which in turn regulate gene expression, have been proposed. Based on the deep link existing among immune and neuroendocrine functions, it is argued here that epigenetic changes could represent the basis for explaining the numerous observations reporting hints of immunological memory in absence of lymphocytes.