Comments on a case report on myocardial infarction.

problem of heterogeneity of 1gM arises in Waldenstr#{246}m macroglobulinemia, collagen diseases, and chronic liver diseases, for example, in which a variable proportion of the 1gM might be monomeric (6). Two problems can arise in these situations: if a single monoclonal fraction is present, one may ask whether it is monomeric or polymeric; a shift in electrophoretic mobility after reduction will indicate the fraction to be polymeric, but the rarity of pure monomeric IgM fractions limits the usefulness of the test. More often-and this is true of all the above-mentioned situationsmixtures of monomeric and polymeric 1gM co-exist, and there would be a strong case for developing a method allowing the easy determination of the polymer/monomer ratio. The electrophoretic procedure described by Krolikowski et al. will not allow such a determination, because it is not quantitative.