Activity of antibodies recovered from immune complexes of ovarian cancer patients

Abstract

Ascites fluids from ovarian cancer patients contain immune complexes (IC). Attempts were made to characterize those antigens to which the patient is reacting using antibody recovered from these complexes. Polyethylene glycol (PEG) precipitation and protein A Sepharose 4B affinity chromatography were used to isolate IC. Dissociation of the IC was achieved by G-150 gel filtration in 0.1 M acetic acid, 0.15 M NaCl. Activity of antibody preparations was measured using a binding assay with 125I-labeled staphylococcal protein A. Confluent monolayers of various cell lines (including human ovarian and cervical carcinoma lines, human lymphoblastoid cell lines, human and chick embryo fibroblasts) were used. Six of nine antibody preparations isolated from ovarian cancer patient IC contained at least some reactivity against all cell types. Specificity was further defined using cell adsorption assays and polyacrylamide gel electrophoresis. These results indicate what appears to be autoreactivity directed against a normal component(s) of many cells. No evidence for an ovarian cancer-restricted response was shown. Immunoprecipitation analyses showed several polypeptide bands on autoradiograms (49K, 46K, 33K, 25K), which deviated distinctly from the pattern obtained for whole cell extracts.

Recovery of a cell surface fetal antigen from circulating immune complexes of melanoma patients

“…The availability of a well-characterized and purified FA greatly simplified our task. Our results demonstrated that (1) A number of antigens have been identified in IC of cancer patients, including TAA [4,8,20], oncofetal antigen [8,26], viral antigens associated with virus-related malignancies [17,29], idiotype/antiidiotype antigens [14], and altered self components [2,5,19]. It is generally agreed that TAA present in CIC of cancer patients comprise only a small fraction of the antigens complexed to antibodies [6].…”

“…However, CIC in an individual may arise from sources other than tumor activity. Antibody [19], antiidiotype [5,15,23] and other altered self components [2,6,18] have been detected in CIC of cancer patients. Since most CIC detection assays are antigen nonspecific, it is not surprising that the clinical utility of CIC analysis in human cancer has been controversial and limited [6,28].…”

Nature of antigens and antibodies in immune complexes isolated by staphylococcal protein A from plasma of melanoma patients

“…For these reasons, it becomes necessary to determine the nature of the antigen(s)in the immune complexes of CIC-positive patients. Although progress in this direction has been slow, the antigen portion of ICs isolated from cancer patients has been identified in some instances [28,29,35].…”