A Method for Further Separation of Specifically purified Antibodies by Liquid Isoelectric Focusing

Specifically purified anti-p-azophenyltrimethylammonium antibodies from individual rabbits have been separated by isoelectric focusing on a preparative scale over a pH range of 5 to 8 into as many as 30 components differing in isoelectric properties and demonstrating reduced heterogeneity. A number of these components have many of the properties characteristic of homogeneous antibodies. The isolated antibodies are electrophoretically discrete and show homogeneous binding properties towards the p125I-iodophenyltrimethylammonium hapten, giving two combining sites/mol protein with a heterogeneity index of 1.00 ± 0.05. On alkaline urea disc electrophoresis, the fully reduced and alkylated antibody light chain patterns were monodisperse. Several specifically purified rabbit and goat antibodies directed against neutral, positively charged and negatively charged haptens have been purified. This procedure appears to afford a general method for the further purification of antibodies to a state suitable for sequence studies and detailed structural studies on the nature of the combining sites.

Studies on Human Myeloma Proteins with Antibody-Like Activity

More than 500 human sera containing one or more M-components were screened for antibody-like activity, using both double diffusion in agarose and modified Farr binding studies. Antibody activity was detected in two IgG myeloma proteins and two IgM macroglobulins using a number of negatively charged, positively charged, and neutral haptens. We have at least one of these M-components growing in cell culture producing two different cell lines, and we have obtained small crystals with two of the M-components. Equilibrium dialysis of the purified M-components yielded K0 values with low affinity. We have isolated, using liquid isoelectric focusing, a homogeneous IgG(γG1, K) protein from a leukemic patient 2 months after a bone marrow transplant operation. The IgG was not directed against the histocompatibility antigens. We detected significant binding with this protein and 3H-hydrocortisone. (Supported by MRC grant MA-3001 and the Ontario Treatment and Research Foundation).