A highly sensitive radioimmunoelectrophoretic quantitation of human alpha-fetoprotein

Labeling immunoelectrophoresis: a general method for increasing the sensitivity of rocket immunoelectrophoresis with 125I-labeled anti-antibodies

In a new procedure, rocket immunoelectrophoresis is performed at pH 8.7 with rabbit antibodies and 5% polyethyleneglycol 6000 in the agarose gel. After the pH in the gel has been changed to 5 the nonprecipitated immunoglobulins are electrophorsed out of the gel simultaneously with the electrophoresis of 125I-labeled swine antibodies against rabbit IgG into the gel. The latter antibodies tag the rabbit IgG, which is not present only in the precipitates. The radioactive precipitates are visualized by autoradiography. The method permits quantification of antigens down to an amount of approximately 0.5 ng; well-defined rockets are not formed below this limit. Compared to conventional protein staining with Coomassie brilliant blue, this represents an increase in sensitivity of up to 20 times.

Suppression of the mitogen response of normal lymphocytes by serum from patients with testicular germ cell tumors

Serum from seven of 15 patients with nonseminomatous testicular germ cell tumors impaired the transformation of lymphocytes from normal donors by phytohemagglutinin to less than 50% of that with addition to the cultures of normal AB serum. Similarly, serum from eight patients impaired the transformation by Staphylococcus aureus Cowan I. The impairment of the lymphocyte transformation did not correlate with the serum concentrations of alpha-fetoprotein (S-AFP) and human chorionic gonadotropin (S-HCG). The patients with metastases and serum that impaired lymphocyte transformation to less than 50% of that with addition of serum from the controls and the other patients survived in the same way (0.50 less than p less than 0.75, log-rank test). The prognosis of patients with testicular germ cell tumors seems not be influenced by S-AFP and S-HCG through an impact on lymphocyte functions determined as the response to the two mitogens.

Analysis of maternal alpha-fetoprotein: a comparison of three radioimmunoassays

Increased levels of alpha-fetoprotein in maternal serum or amniotic fluid may be indicative of a fetal neural tube defect. The present investigation compares, prospectively and retrospectively, the analysis of serum or amniotic fluid alpha-fetoprotein from humans using three radioimmunoassays. A total of 46 sera and 137 prospective and 202 retrospective amniotic fluid samples collected at 12-26 weeks' gestation were assayed using our in-house Farr technique assay, a kit Farr technique assay, and a kit double-antibody assay. Analysis of quality control data in all three assays showed that within- and between-assay variations were less with the double-antibody technique. Additionally, the double-antibody assay offers the advantage of considerably lower nonspecific binding (1.7% vs 16-18% for the Farr technique assays). Of the 375 pregnancies sampled during this study, 340 (91%) resulted in normal singleton births, whereas three (1%) pregnancies were found to have elevated serum or amniotic fluid by all three assay methods and resulted in confirmed neural tube defects. Of the remaining, non-normal outcome without neural tube defect or elevated alpha-fetoprotein was determined in 27 (7%) pregnancies, and false-positive elevated alpha-fetoprotein levels were found for 5 (1%). Analysis of maternal alpha-fetoprotein by radioimmunoassay is a sensitive and accurate adjunct in the prenatal diagnosis of neural tube defects.

Identification of cytosolic antigens from GW-39 adenocarcinoma cells by crossed immunoelectrophoresis and immunofluorescence

Rabbits were immunized with a cytosolic fraction prepared from human adenocarcinoma cells of the colon (GW-39). The antibodies obtained were analyzed using crossed immunoelectrophoresis and were found to precipitate 23 distinct antigens in the cytosolic fraction from colon tumor cells. After preabsorption with human serum and plasma as well as acetone powders prepared from 2 normal human tissues and 4 normal hamster tissues, 1 major immunodominant cytosol antigen (CA-3) and two less intense immunoprecipitin peaks (CA-1 and CA-5) remained detectable by the crossed immunoelectrophoretic method. The preabsorptions with normal tissues were sufficiently complete to remove anti-carcinoembryonic antigen antibodies and showed that antigens CA-1, CA-3 and CA-5 are immunologically distinct from carcinoembryonic antigen. Indirect immunofluorescence localization studies with preabsorbed anti-cytosol antibodies and FITC-conjugated second antibody showed that these antigens were expressed in the cytoplasm and at the cell surface in several human colon tumor cell lines, their subclones and in primary colon tumor specimens.

Serum lactate dehydrogenase and its isoenzymes in men with maldescended testes

Serum lactate dehydrogenase and lactate dehydrogenase isoenzymes were determined as a screen for testicular germ cell neoplasia in 130 men with maldescended testes. A testicular tumor was found on clinical examination in 1 patient, which was revealed to be embryonal carcinoma, teratoma, yolk sac tumor and carcinoma in situ on orchiectomy. Subclinical testicular germ cell neoplasia was found on testicular biopsy in 3 men (1 with microinvasive seminoma and 2 with carcinoma in situ). These 4 patients had normal serum lactate dehydrogenase and serum lactate dehydrogenase isoenzymes. Elevated serum lactate dehydrogenase was noted in 3 men without testicular germ cell neoplasia: 1 had predominantly increased serum lactate dehydrogenase isoenzymes 1 to 3 and 2 had slightly increased serum lactate dehydrogenase isoenzymes 3 and 4. Serum lactate dehydrogenase and lactate dehydrogenase isoenzymes were not sensitive to detect testicular germ cell tumors in a subclinical stage.

Microheterogeneity of alpha-fetoprotein in patient serum as demonstrated by lectin affino-electrophoresis

Microheterogeneity of alpha-fetoprotein (AFP) present in the sera of 76 patients was studied by lectin affino-immunoelectrophoresis. Seventeen patients had benign liver disorders and the remaining 59 patients were treated for primary or secondary liver cancer or yolk sac tumour. By means of Con A, AFP was divided into two variants, while lentil lectin (LCA) made it possible to separate AFP in three variants. In some patients the relative concentrations of Con A and LCA AFP variants were similar; these patients were believed to produce AFP of the same 'profile'. Fourteen AFP profiles were observed by estimation of the area enclosed by precipitates corresponding to respective AFP variants. It was also possible to estimate the AFP profile on the basis of a simple visual analysis of the electrophoretic plates. The obtained results indicate that the AFP profiles of patients with cancer were variable. In spite of variations of the AFP profile in cancer patients, in most cases it was possible to differentiate primary liver cancer from yolk sac tumour and from liver metastases of cancer. In addition, in two-thirds of hepatoma patients the AFP profile was different from the profile observed in patients with benign liver disorders.

Pregnancy-associated plasma protein A: circulating levels during normal pregnancy

The development of specific and sensitive electroimmunoassays for a recently identified high molecular weight alpha-2 mobile pregnancy-specific protein (pregnancy-associated plasma protein A, PAPP-A or SP4) is described. These assays have permitted the detection of circulating levels of PAPP-A (10 microgram/L) as early as the fifth week of pregnancy. In all 18 subjects studied, the levels of PAPP-A rose from first detection in the first trimester until delivery at term. The development of these assays now permit the evaluation of PAPP-A measurement as a diagnostic test of early pregnancy and as an index of fetal well-being throughout gestation.

Circulating levels of pregnancy zone protein: normal range and the influence of age and gender

Serum levels of pregnancy zone protein (PZP) were measured in 506 apparently normal males and 329 normal non-pregnant females, the age range being 18 to 70 years. The estimations of PZP were performed by sensitive radio-rocket-line immunoelectrophoresis. The distribution of the data had a marked positive skew in both sexes which was reduced following logarithmic transformation. Serum concentrations in both men and women were found to increase significantly with advancing age. This increase and the mean concentrations were significantly higher in females.

Alpha-fetoprotein: a review

Alpha fetoprotein (AFP) is the major protein of fetal serum and most resembles albumen, which replaces it shortly after birth. It is produced by fetal liver and passes into the amniotic fluid (AF) via fetal urine. A small amount crosses the membranes into the maternal circulation. Excluding fetal blood contamination, elevated AF/AFP levels indicate fetal demise or one of several abnormalities. Maternal serum (MS) AFP measurement can be used as a screening procedure to identify neural tube defects providing a rigorous protocol is followed. This requires that a laboratory establish its normal range of MS/AFP levels between 15 and 20 weeks gestation, employ a reliable assay with adequate controls, and has recourse to genetic counseling as well as expert sonography, amniocentesis and amniography if necessary. Pregnancy is the only normal situation in which AFP is present after birth. It may be present in high levels in certain malignancies and has been useful in monitoring their recurrence. This article will review the history, biochemistry, and different assays of AFP in AF and blood as well as the indications and limitations for their use.

Characterization of a human ovarian teratocarcinoma-derived cell line

A cell line (PA I), derived from human ovarian teratocarcinoma cells, was obtained by culturing ascitic fluid cells from a patient with recurrence of malignant ovarian teratoma. During early passages the cultured cells showed a variable morphology, a long doubling time, and a low plating efficiency (2%). After about 50 passages in vitro, a cell population which was more homogeneous and resembled embryonal carcinoma cells were obtained. These cells had a shorter doubling time (26 h), and increased plating efficiency (77%). The early-passage cells were aneuploid (P 24) whereas the late-passage cells had a normal diploid karyotype with one balanced translocation between chromosomes No. 15 and No. 20 (P 224). Details of the karyotype suggest that the cells are heterozygous, i.e. derived from a stage before the first meiotic division. One of the two X chromosomes were inactive, and the cells expressed HLA antigens (A28 and B12), and beta 2-microglobulin. Expression of F9 antigen, characteristic of two-cell and later preimplantation embryos, was absent, while expression of PCC4 antigen, expressed also by blastocysts, was present. This finding suggests that the line might express some embryonic characteristics. The PA I cell line maintained in monolayer cultures showed several characteristics of malignant cells. The proportion of malignant cells increased with successive passages in vitro. The late-passage cells represented a fairly homogenous population of malignant cells similar to embryonal carcinoma cells. Late-passage PA I cells, when seeded under conditions that prevented attachment of cells to the substratum, formed embryoid bodies consisting of an inner core of cells similar to embryonal carcinoma cells, surrounded by a rind of endoderm-like cells. These two cell layers were separated by a basement membrane-like structure containing fibronectin. The core embryonal carcinoma cells expressed high alkaline phosphatase activity whereas the endoderm-like cells had low alkaline phosphatase activity. Embryoid bodies seeded on an adhesive substratum formed polycystic structures divided by layers of epithelial-like cells and containing extracellular fibrils similar to collagen type I or III. In these cultures, further limited differentiation into endoderm-like, epithelial-like cells and pigmented cells was observed. Morphological differenciation of undifferentiated PA I cells into endoderm-like cells in monolayer cultures could be obtained by treatment with BrdUrd or by plating in low serum concentration and at low density. Cells with characteristic fibrillar distribution of fibronectin and actin microfilament bundles were then observed, indicating formation of cells lacking properties of malignant cells. As indicated by these results, the PA I cell line, in spite of a limited capacity to differentiate in vitro, shares some of the properties of mouse teratocarcinoma cell lines and might therefore serve as a useful model for studies on some developmental mechanisms in human cells.

Serum alpha-fetoprotein as a marker for the effect of post-operative radiation therapy and/or chemotherapy in eight cases of ovarian endodermal sinus tumour

The clinical pathological findings of eight cases of ovarian endodermal sinus tumour (yolk sac tumour) are presented. Histological exmination in all eight cases showed a typical endodermal sinus tumour pattern, and in six of the patients other tumour elements such as dysgerminoma, choriocarcinoma, malignant teratoma, endometriosis, and a dermoid cyst were also found. Six patients had increased serum alpha-fetoprotein concentration in the post-operative period, and two patients had a normal concentration 27 and 35 days after operation, respectively. In all cases except one, a close correlation between serum alpha-fetoprotein and progression or regression of tumour was found. Serum alphafetoprotein was thus found to be a reliable parameter in post-operative radiation and/or chemotherapy (VAMBLE). In one patient who died 10 months after operation with widespread endodermal sinus tumour growth, only a small terminal increase in serum alpha-fetoprotein concentration was found. Four of the eight women are still alive with normal alpha-fetoprotein concentration, and without clinical evidence of tumour disease.

Alpha-fetoprotein-like activity in sera from patients with malignant and non-malignant disease and healthy individuals

A new method, radio-crossed immunoelectrophoresis, demonstrates alpha-fetoprotein (AFP) in sera with a sensitivity of 1 mug/1. By this method AFP with alpha mobility was not found in sera from healthy individuals, patients with chronic active hepatitis and cirrhosis, primary biliary cirrhosis, secondary liver cancer and cystic fibrosis. In some of the sera, AFP was elevated when measured by conventional radioimmunoassay method and the sera contained an AFP-like substance with gamma mobility when analyzed by radio-crossed immunoelectrophoresis. The nature of this gamma substance is still obscure and needs further investigation.

Radioelectroimmunoassay of anti-D immunoglobulin on agarose plates containing whole red cells

By incorporating whole Rh(+) red cells in an agarose plate and adding a small amount of purified 125I anti-D immunoglobulin as a tracer to standards and samples, a radioelectroimmunoassay (REIA) of anti-D immunoglobulin was possible. The results by this method agree with those obtained by the direct method. The coefficient of variation (within plate precision) is less than 9% and the reproducibility is 12% (coefficient of variation for a plasma sample assayed on six occasions during 1 month). The International anti-D serum was compared with the WHO standard preparation 68/419 on five occasions and found to contain 11; 11; 10; 9 and 11 mug per ampoule.

Alpha-fetoprotein

Despite all the information about AFP presented, a great deal still needs to be discovered especially in pregnancy. Geographical and racial differences remain to be elucidated. Similarly, differences in obstetric population in Helsinki and Baltimore, for example, are only now being studied. Sex differences may exist; Lardinois and associates195 cited a higher level of AFP in male than female fetuses. The important questions that need to be answered are whether AFP assays can help improve the other half of prenatal care- that directed to the fetus- and whether the AFP model can help enhance our understanding of the similarities and differences of fetal and cancer cells.

Reference interval for maternal serum alpha-fetoprotein

Maternal serum alpha-fetoprotein (AFP) concentration was measured in 237 samples taken throughout the pregnancies of 28 normal pregnant women who all gave birth to normal infants. The patterns from these 28 individuals curves were compared graphically with an earlier published non-parametric 90% reference interval based upon single serum samples from other normal, pregnant women. The two "reference areas" were found to be quite similar. Maternal serum AFP values before and after induced abortion in a case of acrania and spina bifida demonstrated the value of serial maternal serum AFP quantitations in cases of suspected neural tube defects (NTD).

Serum alpha-foetoprotein as a marker for endodermal sinus tumour (yolk sac tumour) or a vitelline component of "teratocarcinoma"

The correlation between serum alpha-foetoprotein (AFP) and the clinical pathological finding of 24 germ cell tumours arising from the testes (14 cases), the ovaries (3 cases), the mediastinum (3 cases), the retroperitoneal region (2 cases), and the sacrococcygeal region (2 cases) are presented. Irrespective of marked differences in age and sex of the patients, primary site of the tumours and clinical outcome, the 24 cases constituted a homogeneous group in fundamental histological patterns and in AFP synthesis. In all cases of endodermal sinus tumour or teratocarcinomas with a distinct vitelline component an increased serum AFP concentrations was found in the pre-operative serum samples. AFP was also demonstrated in the tumour tissue by quantitative determination of AFP in tumour homogenate (5 cases) and, by immunofluorescence technique, positive staining of the cells lining the endodermal sinuses and of the hyaline globules was found (3 cases). In 12 germ cell tumours without vitelline components in the tumour tissue sections, a normal AFP concentration below 20 mug/1 was found in preoperative serum samples.

Alpha-feto-protein during development and in disease

An alpha-feto-protein (AFP) is present in many mammals, in birds, and in sharks during development. The AFP present in different species have similar physicochemical properties and often have common antigenic determinants. Their study, both in health and disease, has provided a useful model for the understanding of other phase-specific antigens and the activation of the genes which control their synthesis. In the human fetus, the level of AFP falls with increasing maturity. The more sensitive methods of detection have disclosed that this fetal protein persists in trace amounts throughout life and its level increases in maternal blood during pregnancy. The principal sites of synthesis are the fetal liver and in some mammals, the yolk sac splanchnopleur. In humans as well as in mice and cows, it is notable that the synthesis of AFP is increased in liver cancer cells and that high levels of this protein are present in serum. Elevated values of AFP have also been detected in human subjects with undifferentiated tumours of the testis and ovary. A fall to normal levels has been noted in cases of complete remission after surgery and a return to high levels in patients who develop metastases. In some patients with hepatitis a temporary rise in the level of AFP has also been observed. In recent years, the detection of high levels of AFP in amniotic fluid has proved to be of great value for the prenatal diagnosis of neural-tube defects. Abnormal levels have also been found in the amniotic fluid or in maternal serum in cases of spontaneous abortion. Such measurements are now being assessed as a methodof monitoring abnormal pregnancy.

[Carcinofetal antigens. I. alpha-fetoprotein (author's transl)]

Alpha-fetoprotein (AFP) is an alpha1-glycoprotein (M.W. about 65000) appearing in the fetal serum of most mammals including man during the early stages of pregnancy; 4 weeks after birth it disappears altogether or exists at very low concentrations as in the normal adult. AFP is formed in the yolk sac, the fetal liver and the gastro-intestinal tract. One of its physiological functions in fetal life is supposed to be the protection of the fetus from maternal oestrogens (oestrophilic property). The clinical significance of AFP is based on the regular and increasing production in primary liver cell carcinoma, less frequently in teratogenetic tumors where it serves as a control of therapy and course of the disease. Less frequent, minor and temporary increases in the AFP serum level occur in several primary tumors with secondary liver involvement, and in inflammatory gastro-intestinal diseases, e.g. of the liver (hepatitis, cirrhosis). AFP has an increasing importance in gynecology (gestational age, fetal distress syndrom, malformations, hydatidiform mole/chorion carcinoma). The physico-chemical properties of AFP are widely known. Both fetal and tumor AFP appear to be immunologically and biochemically identical, as are that of tissue and biological fluids. The differences observed (variants, microheterogeneity) depend mainly on the different content of sialic acid. An antigenetic relationship exists, between the AFP of most species. The immunodiffusion (Ouchterlony) is the most frequently used but relatively insensitive test (1-5 mug/ml) in finding AFP, whereas the radioimmunoassay is the most sensitive one (up to 0,25 ng/ml) and permits the determination of normal serum levels in adults (below 20 ng/ml). The serum concentration in healthy pregnant women lies up to 500 ng/ml, in patients with hepatitis, liver cirrhosis and other liver diseases mostly under 3 mug/ml, whereas in those with primary liver cell carcinoma levels up to and above 600 mg-percent have been found.

Alpha fetoprotein levels in maternal serum and in amniotic fluid from early normal pregnancies

Alpha fetoprotein (AFP) was determined in serum from 241 women in the 8th to 43rd week of gestation by quantitative radioimmunoelectrophoresis, and in 103 amniotic fluid samples from the first half of pregnancy by rocket immunoelectrophoresis. Both serum and amniotic fluid samples were obtained from a larger material, but samples were included only from pregnant women whose infants were normal at birth. The 90% normal AFP range was calculated both for maternal serum and for amniotic fluid.

Elevated levels of alfa fetoprotein in maternal serum and amniotic fluid in two cases of spina bifida

Therapeutic abortions were performed in two cases of spina bifida which were diagnosed by determination of the lafa fetoprotein levels in the amniotic fluid and maternal serum.