Assay, Isolation and Characterization of Circulating Immune Complexes from Serum of Gastrointestinal Cancer, Stage III and IV Melanoma and Chronic Inflammatory Bowel Disease Patients

Abstract

Circulating immune complexes (CIC) have been detected in several autoimmune diseases, and studies have also suggested that CIC provide a useful tool as tumor markers. In order to identify differences or similarities in antigenic composition, CIC from 23 patients with gastrointestinal (GI) tumors, from 20 patients with stage III and IV melanoma and from 6 patients with inflammatory bowel disease (IBD) were studied. Serum from all GI, melanoma and IBD patients showed higher levels of CIC than controls. SDS/PAGE electrophoresis under reducing conditions revealed some differences between cancer and IBD patients as far as the CIC protein composition was concerned. In melanoma patients, two fast-migrating bands, in the regions of 71–74 and 30–49 kD, were found, consistent with previously isolated and characterized antigens described in the literature.

Antitumor Effect of an Antibody Against Gastrointestinal Cancer–Associated Antigen CA19.9

“…Although evidence for a circulating Ag-Ab complex has been discovered in patients with colorectal cancer, significant increments in measurable plasma antigens have been observed in most cancer patients. 14,22 Thus, external Abs become necessary to eliminate the immunosuppression of antigens. Systemic administration of external monoclonal antibodies has already shown clinical promise, [23][24][25] and increasing numbers of mAbs are now becoming components of standard treatment regimens.…”

Leaky gut, circulating immune complexes, arthralgia, and arthritis in IBD: coincidence or inevitability?

“…The gut immune system, the body’s largest and most intricate immune compartment ( 29 ), comprises two primary domains of B cell lineages. These encompass the organized B cell clusters residing in the gut-associated lymphoid tissue (GALT) and the diffuse lymphoid tissues spanning the extensive lamina propria of the small and large intestines ( 30 ).…”

“…Elevated CIC levels have also been demonstrated in patients with IBD ( 29 ), and these levels correlate with disease activity and systemic presentation ( 45 ). Considering the presence of antigen-antibody responses in an inflamed gut, complement system activation would be expected.…”