Flow cytometry and immunoblotting analysis of monoclonal antibodies directed to CD-related antigens

Soluble CD44: quantification and molecular repartition in plasma of patients with colorectal cancer

Based on the important role of CD44 in tumour progression and metastasis, we evaluated, in a prospective study, plasma-soluble CD44 (sCD44) as a serum marker in colorectal cancer. Blood plasma specimens from 89 patients with colorectal neoplasm, 22 patients with a gastrointestinal disease and 23 healthy donors were analysed for quantitation (ELISA assay) and purification of sCD44. The concentration of sCD44, indicating the concentration of all isoforms, was significantly higher in patients with colorectal cancer and intestinal disease than in normal individuals, but no significant differences were found between the two groups. We found no association between plasma levels and staging of the colorectal cancer patients according to Astler and Coller. A two-step batch purification combining ion exchange and immunoaffinity chromatography, followed by Western blot analysis, revealed a complex pattern with a major band corresponding to the standard form of CD44 and minor bands that may correspond to larger variant forms. No particular sCD44 isoform was clearly associated with anatomopathological or biological information.

Flow cytometry and immunoblotting analysis of monoclonal antibodies directed to complement regulatory proteins

A series of 18 monoclonal antibodies directed to complement regulatory proteins were investigated by flow cytometry and immunoblotting. Seventeen antibodies are directed against a phosphatidyl inositol-linked glycoprotein since they show a dual population of erythrocytes from a paroxysmal nocturnal haemoglobinuria (PNH) patient. From this group, 6 antibodies revealed a 65-70 kDa band on immunoblots allowing their identification as anti-DAF (Decay Accelerating Factor; CD55 antigen), and 11 bound to a 20 kDa molecule corresponding to MIRL (Membrane Inhibitor of Reactive lysis, CD59 antigen). One antibody revealed an homogeneous population from the PNH patient and bound to a 200 kDa band on immunoblot that might corresponds to the CR1 (Complement Receptor type 1; CD35).