Type IV collagen and laminin-related antigens in human serum in alcoholic liver disease.

The two major constituents of basement membranes are type IV collagen and laminin. Specific radioimmunoassays are described here for two structural domains of these proteins (7-S collagen and the fragment P1, respectively) that allow the related antigens to be quantified in human serum. The serum 7-S collagen antigen was uniform in size, whereas the laminin P1 antigenicity was heterogeneous. These proteins were measured in sera from sixty-three alcoholics, divided on the basis of liver histology into four groups: normal light microscopy, fatty liver, alcoholic cirrhosis with hepatitis and inactive cirrhosis. The group with cirrhosis and hepatitis had clearly elevated values in both assays, differing significantly from the others. A few pathological results were also seen in the other groups. The increases noted in 7-S collagen concentration were larger than those in laminin P1. During follow-up of a patient with cirrhosis and hepatitis the 7-S collagen level in particular seemed to reflect the course of the disease. The elevated basement membrane protein concentrations in serum may be associated with the formation of real basement membranes in the perisinusoidal space, a process known as capillarization of the sinusoids which is found during the development of liver cirrhosis.