Identification of an IgD-like surface immunoglobulin on rabbit lymphocytes

Rabbit immunoglobulin antigen receptor molecules were analyzed by electrophoresis in sodium dodecyl sulfate polyacrylamide gels. By sequential precipitation, using first anti-mu and then anti-L chain antisera, two different immunogloublins of similar molecular weight could be demonstrated. After tryptic digestion, two fractions were identified: an IgMs and an Fab fragment, the latter appearing after a few minutes of incubation. Thus, as in man and in the mouse, two main immunoglobulin antigen receptors were found in the rabbit. One receptor on rabbit lymphocytes is an IgMs molecule, and the other is easily split in the hinge region like human and mouse IgD receptors. In addition, a molecule similar to the mouse Fc receptor was nonspecifically precipitated.