The carcinoembryonic antigen (CEA) of normal and pathological tissue extracts was separated into two variants, Concanavalin A reactive (CEAr) and non-reactive CEA (CEAn) by affinity chromatography on Con A Sepharose columns. CEAr was the quantitatively predominant variant. CEAn varied in concentration between 0.2 and 6 percent of the total CEA activity. The affinity of CEAn for anti-CEA antibodies was significantly lower than that of CEAr. Pooled extracts of primary adenocarcinomas of the colon contained CEAn in the lowest concentration and with the least affinity for antibodies. It is suggested that a deficiency and/or steric blocking of alpha-D-mannopyranosyl residues in CEAn reduce the affinities for both antibodies and Con A.

Adenocarcinoma↗

PubMed1975

Rapid radioimmunoassay of carcinoembryonic antigen (CEA) in ultrafiltered perchloric acid extracts: results of a clinical survey.

Perchloric acid treatment of the carcinoembryonic antigen (CEA) results in subunits of approximate mol. wt 40 000 to 50 000 with different electrophoretic mobilities and amtogenic deficiences as demonstrated by immunoelectrophoresis. An improved radioimmunoassay is described for the quantitation of CEA using rapid ultrafiltration of serum or plasma extracts. The assay was designed to take into account the changes CEA undergoes during perchloric acid extraction. Absorption of antibodies against a crossreacting non-specific antigen from CEA antiserum did not improve the specificity of the radioimmunoassay as was shown by clinical use of the test in almost 1800 patients.

Animals↗

PubMed1975

Radioimmunoassay of beta2-microglobulin.

A radioimmunoassay for quantitation of beta2-microglobulin in serum and urine is described. Polyethylene glycol 6000 was used to precipitate the antigen-antibody complex. The assay can be performed within 5 hr. In healthy human subjects (mean age, 30.6 years and 42.0 years for serum and urine determinations, respectively) the mean concentration of beta2-microglobulin in serum was 125 nmol/l (range, 49-190 nmol/l). In men the mean 24-hr urinary excretion was 12.9 nmol (range, 8.6-19.2 nmol), and in women it was 5.5 nmol (range, 2.9-8.7 nmol). The assay range was 0.23-19.40 nmol/l, and the detection limit was 0.042 nmol/l, using a prolonged incubation time. The coefficient of variation based on 20 determinations in serum dilutions with a concentration of beta2-microglobulin of 8.14 and 1.92 nmol/l was 8.1 per cent and 9.0 per cent, respectively.

Adult↗