Immunoglobulin classes in the garden lizard,

Two classes of immunoglobulins have been purified from lizard serum using a combination of ion-exchange chromatography on DEAE-cellulose and gel filtration on Sephadex G-200 or on Sepharose 6B. Lizard IgM is 2-ME sensitive and has an intact molecular weight similar to human IgM. On SDS-PAGE, reduced IgM dissociates into heavy and light chains of molecular weight 70,000 and 23,500 daltons respectively. Lizards also possess a 2-ME resistant, low molecular weight immunoglobulin designated as IgY similar to avian and amphibian IgY. IgY dissociates on SDS-PAGE to yield 59,500 dalton heavy and 26,000 dalton light chains. Antisera raised in rabbits to each of the two Ig classes could be made class-specific by cross-absorption, thus indicating that IgM and IgY represent distinct isotypes.