[IgG subclasses in malignant melanoma].

The 397 sera from 185 melanoma patients have been studied and classified in three groups according to the stage of disease. Our findings revealed an alteration of the level of IgG4 subclass which is related to the dissemination of disease. The percentage of abnormalities (either increased or decreased levels of IgG4) was more frequent in stage II and III (55% and 53% respectively) than in stage I (19%), The higher frequencies of high titers of IgG4 were essentially detected in advanced disease. The biological significance of the increase of IgG4 in melanoma remains obscure. It may be related to the development of facilitating antibodies of IgG4 subclass.