Ig in the evolutionary scale???

[Joao Alexandre R.G.Barbosa]

     Hi,

        I was discussing about Imunoglobulins (Ig) the day, when sudenly I
found out that I didn't know until where the Ig or a folding/function like
protein exists in the evolutionary scale. I mean, when and where
(invertebrates, fishes, anphibians, reptiles ...) did they appear ? How is
the imune response of these animals without Ig ?

                        Thank you, Joao.
                                          jargb at ifqsc.ansp.br