Subject(s)
Erythrocytes/metabolism , Erythroid Precursor Cells/metabolism , Ferritins/metabolism , Iron-Binding Proteins , Lymphocytes/metabolism , Receptors, Cell Surface/metabolism , Reticulocytes/metabolism , Cell Differentiation , Cell Division , Cell Line , Deferoxamine/pharmacology , Ferritins/pharmacology , Humans , Leukemia, Erythroblastic, Acute/pathology , Liver/embryology , Lymphocyte Activation , Neoplasm Proteins/metabolism , Protein Binding , Recombinant Proteins/pharmacology , Tumor Cells, Cultured/metabolismABSTRACT
Monoclonal antibodies (mAbs) with a high sensitivity and specificity for small cell lung cancer (SCLC) may be of potential diagnostic and therapeutic use. We selected five different mAbs generated against SCLC cell lines and tested them on paraffin-embedded SCLC and non SCLC (NSCLC) clinical samples in a retrospective study using immunohistochemical techniques. The results showed that the contemporary use of mAbs that react with different antigens allowed all the examined SCLC to be detected indicating that this panel of mAbs was extremely sensitive. Analysis of the reactivity of these mAbs with NSCLC showed that 4 of the 5 antibodies reacted also with a few NSCLC. Using higher dilutions of these mAbs their specificity improved substantially. The 5 different mAbs presented marked heterogeneity of antigenic expression within and between SCLC. This panel of antibodies may be very useful in the diagnosis of SCLC whereas their application, in vivo, in therapeutic trials, is limited by the heterogeneity of antigenic expression.
Subject(s)
Antibodies, Monoclonal , Carcinoma, Small Cell/diagnosis , Lung Neoplasms/diagnosis , Antibodies, Monoclonal/immunology , Antigens, Neoplasm/analysis , Carcinoma, Non-Small-Cell Lung/immunology , Carcinoma, Small Cell/immunology , Humans , Immunohistochemistry , Lung Neoplasms/immunologyABSTRACT
Purified recombinant human ferritin composed solely of H subunit was radiolabeled and incubated with proerythroleukemic K562 human cells. A specific binding was detected, and it could be displaced only by ferritins, natural or recombinant, containing large proportion of the H subunit. The specific ferritin H-chain binding was saturable, and cells showed 17,000 to 23,000 binding sites per cell. The affinity constant measured at 37 degrees C was of 3 x 10(8) M-1. Treatment with pronase eliminated the specific binding. The binding sites were expressed in a high number during the cellular exponential phase of growth and progressively decreased to disappear when cells reached the plateau phase. Treatment of the cells with desferrioxamine increased recombinant H-ferritin binding, while iron had little effect. K562 cells induced to differentiate by hemin failed to bind ferritin H. Ferritin H-chain binding capacity is present on various cell lines such as HL60, lung cancer, and hepatoma cells. Analysis of the binding sites by western blotting showed a peptide with apparent mol wt of about 100 kd.
