Cryoglobulins in Behçet's syndrome and recurrent oral ulceration: assay by laser nephelometry.

The presence of cryoglobulins was investigated in ninety patients with recurrent oral ulcers (ROU) and sixty-one patients with Behçet's syndrome (BS). The immunodiffusion method was compared with Laser nephelometry for the analysis of IgG, IgM, IgA and C3 in cryoglobulins. Although the two methods of assessment showed a very significant agreement. Laser nephelometry was more sensitive than the double diffusion precipitation method and was used for quantitative analysis of cryoglobulins. The prevalence of any type of cryoglobulins was 64% in ROU and 75% in BS, as compared with controls (15%). In ROU significant levels of IgA were found in minor (P = 0.0196) and major (P = 0.0114) aphthous ulcers and to a lesser extent in herpetiform ulcers (P = 0.0624). Among the four types of BS signficant increases in C3 were found in the arthritic type (P = 0.0068) and ocular type (P = 0.0275), whereas IgM (P = 0.0031) and IgG (P = 0.0369) were increased only in the muco-cutaneous type. Sequential studies showed that disease remissions or exacerbations were correlated with a decrease or increase in IgM or IgG classes of cryoglobulins. However, the converse was found with IgA which may inhibit some functions of polymorphonuclear leucocytes, and this may be responsible for the failure to remove damaging IgG, IgM and C3 complexes from the circulation.