The frequency distribution of heavy chain classes and light chain types of 1,000 monoclonal immunoglobulins.

In 1000 patients with monoclonal gammapathies, heavy and light chains typing of the monoclonal Ig was performed. Class distribution of the heavy chains showed the following percentages : IgG = 56.60%; IgA = 17.0%; IgM = 14.5%; IgD = 0.3%; Light chain gammapathies (including Bence-Jones proteinuria without serum M-component) = 11.6%. The chi/lambda ratio was 663/337. Such results agree with figures from most statistical studies. Beside the well-known linkage between IgM and chi types in pathological macroglobulinemia, the quite high incidence of lambda chain type of light chain components is to be noticed. The frequency of gamma G type of M-component is significantly higher in patients demonstrating no symptoms of myeloma or lymphoma. chi/lambda ratio seems to be slightly affected by aetiological features.