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ACTH-like activity in immune complexes of patients with oat-cell carcinoma of the lung
Immune complexes could be isolated from sera of 7 patients with oat-cell carcinoma of the lung, but not from 5 normal controls, using zonal ultracentrifugation. After ultracentrifugation, fractions containing macromolecular IgG were absorbed on a protein A-sepharose column and the immune complexes were eluted and dissociated by glycin-HCl buffer at pH 3.5. The eluates were tested for the presence of tumour-associated proteins as carcinoembryonic antigen (CEA), non-specific crossreacting antigen (NCA), alpha2 pregnancy associated antigen (alpha2PAG) and isoferritin. Whereas none of these tumour-associated antigens could be demonstrated, an ACTH-like activity was detected in the immune-complex fractions of 4 patients with oat-cell carcinoma, by radioimmuno- and bioassay. Polyacrylamide electrophoresis of an immune-complex fraction from a patient with Cushing syndrome showed ACTH-like activities, with mol. wt of 110,000, 75,000, 30,000 and less than 20,000 (all glycoproteins) indicating the presence of different subfractions of big ACTH.
Immune complexes could be isolated from sera of 7 patients with oat-cell carcinoma of the lung, but not from 5 normal controls, using zonal ultracentrifugation. After ultracentrifugation, fractions containing macromolecular IgG were absorbed on a protein A-sepharose column and the immune complexes were eluted and dissociated by glycin-HCl buffer at pH 3.5. The eluates were tested for the presence of tumour-associated proteins as carcinoembryonic antigen (CEA), non-specific crossreacting antigen (NCA), alpha2 pregnancy associated antigen (alpha2PAG) and isoferritin. Whereas none of these tumour-associated antigens could be demonstrated, an ACTH-like activity was detected in the immune-complex fractions of 4 patients with oat-cell carcinoma, by radioimmuno- and bioassay. Polyacrylamide electrophoresis of an immune-complex fraction from a patient with Cushing syndrome showed ACTH-like activities, with mol. wt of 110,000, 75,000, 30,000 and less than 20,000 (all glycoproteins) indicating the presence of different subfractions of big ACTH.