Immunodetection of IgM, IgT and pIgR in mucosal tissues of the Antarctic teleost Trematomus bernacchii

We have previously investigated the immune response at hepato-biliary level in the Antarctic teleost Trematomus bermacchii, a species belonging to the Perciform suborder Notothenoidei, the most abundant component of the fish fauna living in the Antarctic ocean. By that time only the IgM isotype was known and well characterized at molecular and biochemical levels in Antarctic fish. Over the past few years we have cloned and sequenced genes encoding other two key molecules of the mucosal immune system, IgT and polymeric Ig receptor (pIgR) of T. bernacchii. The present study aimed at investigating the localization in mucosal tissues of IgM, IgT and pIgR in an attempt to clarify the protein occurrence and transepithelial transport. Biochemical and immunohistochemical data provided convergent data about specific mechanisms operating apical release of IgT in exocrine way, as well as depicting peculiar (maybe ancestral) features compared with well-known mechanisms described for polymeric Igs transport in mammalian tissues.