Two-site immunoassays for the measurement of serum laminin: correlation with breast cancer staging and presence of auto-antibodies.

1. Binding to and destruction of basement membrane (BM) are necessary steps for cancer cells to extravasate and metastasize. Serum levels of released BM components may correlate with the staging of human cancers or with inflammatory disorders. Furthermore, released material may also induce autoantibodies. Since laminin, an 800-kDa glycoprotein, is present in the extracellular matrix, serum laminin levels may be markers of BM injury. 2. A two-site enzyme immunoassay and a radioimmunoassay were developed to test sera from patients with breast cancer or systemic lupus erythematosus (SLE). 3. A significant difference in laminin concentrations was demonstrated between early (T0-T2) and advanced (T3-T4) tumors (P = 0.001). However, specimens from SLE patients did not differ in laminin concentration from normal individuals and no correlation was observed between laminin levels and anti-laminin auto-antibody titers. 4. These results suggest that serum laminin levels are useful markers of BM damage and could be of prognostic value in cancer.