IMMUNOHISTOCHEMISTRY OF GUT-ASSOCIATED LYMPHOID-TISSUE OF THE SEA BASS DICENTRARCHUS-LABRAX (L)

Histology revealed scattered lymphoid cells at all levels of the diges tive tract of the sea bass Dicentrarchus labrax (L.), notably in the m ucosa and submucosa. Immunohistochemistry with monoclonal antibodies a gainst T cells (DLT15) and immunoglobulin-bearing cells (DLIg3 and DLI g13) demonstrated the presence of a gut-associated lymphoid tissue. Qu antitative analysis showed that the concentration of DLT15-positive ce lls largely exceeded that of Ig-bearing cells, while the number and th e distribution of DLIg3- and DLIg13 immunoreactive cells were superimp osable. an apparent gradient in the number of lymphoid cells was prese nt, concentrating them towards the anus. This suggests that, as in oth er fish species, the posterior gut acquired higher immunological relev ance. (C) 1997 Academic Press Limited.