Immunoglobulins and Antibody-Production in Amphibians

Abstract

SYNOPSIS. Recent evidence suggests Ihat amphibians represent a key transition stage in the evolution of immunological competence. In particular, anuran amphibians exhibit a significant advance relative to more primitive vertebrates in their capacity to synthesize two distinct classes of immunoglobulins in response to antigenic stimulation.These two classes of antibody molecule resemble the γM and γG antibodies of man in size and polypeptide chain structure. Furthermore, cellular aspects of antibodyproduction in anura resemble those of mammals in the method of retention of antigen and the range of antibody-forming cells (lymphocytes to plasma cells). In addition to these parameters of antibody-formation, a state of specific nonresponsiveness (high zone tolerance) can be induced in adult anura by pretreatment with large doses of protein antigen. Studies of larval anurans establish that these forms become immunologically competent early in development, but possess only γM immunoglobulins. These larval stages provide feasible model systems for the study of the activation of genes which specify immunoglobulins. Antibody-formation in urodeles is discussed in relation to the emergence of immunological competence in amphibians.