Abstract
In this paper, we summarize our five‐year observation of two‐dimensional polyacrylamide gel electrophoretic (2‐D PAGE) analysis of immunoglobulin (Ig) light (L) chain patterns on serum/plasma and/or purified human Ig, and compare this technique with agarose electrophoresis and/or immunofixation examination. Polyclonal Ig L chains were seen as large “fuzzy” areas with several zones of high density. The majority (71%) of the monoclonal Ig L chains of monoclonal gammopathy detected by conventional electrophoresis appeared as a single large and well‐defined spot on 2‐D PAGE analysis, with the remaining appearing as multiple spots. The presence of oligoclonal Ig, reflected by multiple spots in 2‐D PAGE, and several bands in immunofixation, was observed in 5 of 26 patients after allogeneic bone marrow transplantation and in 5 patients with tumors. In the majority (77%) of hypergamma‐globulinemia, L chains appeared as a wide spread of small and well‐defined spots in 2‐D PAGE analysis. This pattern suggested oligoclonal Ig‐secreting B cell clone expansion, and corresponding abnormalities were not detected with immunofixation. 2‐D PAGE analysis also detected oligoclonal Ig expansions whereas conventional electrophoretic examination was normal in 10 additional patients after bone marrow transplantation, and in 6 of 10 immunocompetent patients with acute severe infections. Analysis of the Ig L chain pattern of a severe combined immune‐deficient mouse populated with human peripheral blood leukocytes confirmed the skewed human Ig production in the model. In summary, 2‐D PAGE appears to be a sensitive tool for the analysis of Ig diversity in various clinical situations.