Amino acid sequence at the N‐terminal end of a cold agglutinin Kappa chain

Most structural studies on the immunoglobulins have been performed on the unique proteins found in the serum and urine of patients with myeloma and Waldenstrom’s disease because these proteins are usually present in large amounts, and are chemically and immunologically sufficiently homogeneous to be considered monoclonal. However, an antibody activity has not been shown for the vast majority of these immunoglobulin proteins. In contrast, most antibody preparations are present in small amounts and are too heterogeneous to allow detailed structural study. To establish a correlation between antibody structure and specificity, it would be helpful to study a group of antibodies which were chemically homogeneous and which had similar specificity, in other words, a group of monoclonal antibodies. The cold agglutinins found in the chronic cold agglutinin disease are known to be unusual antibodies. They are often present in serum in large amounts, are sufficiently homogeneous to appear as single narrow bands in the beta-gamma region [ 1,2] on cellulose acetate electrophoresis [3] , and have almost exclusively light chains of the Kappa type [4]. Recent studies [5] of the alkaline urea starch gel electrophoresis of a series of cold agglutinin light chains showed these to be comparable to Bence-Jones light chains in their degree of homogeneity [6]. This report provides evidence based on amino acid sequence analysis that these agglutinins are monoclonal antibodies. The anti-1 cold agglutinin from a patient (Ste) with chronic cold agglutinin disease was purified from the serum by absorption onto red cell stroma at 0-2OC and elution at 37OC, followed by Sephadex G-200 Gel filtration as described elsewhere [5]. The preparation