Production and characterization of monoclonal antibodies to anti-human chorionic somatomammotropin by immunization with two free synthetic peptides

The peptides corresponding to the fragments 135-140 and 166-174 of human chorionic somatomammotropin (hCS) were synthesized, and used to raise monoclonal antibodies to the native hCS molecule. The synthetic peptides were injected into BALB/c mice in the free form, i.e. not conjugated to a carrier, and the spleens were fused with Sp2/01Ag8 myeloma line to produce monoclonal antibodies. The antibodies produced belonged to the IgM and IgG classes and, once purified by affinity chromatography on hCS-Sepharose, they were covalently coupled to macroporous polystyrene beads and characterized by competitive radioimmunoassay. Their affinity constants were determined by elaborating the radioimmunoassay data by nonlinear regression analysis and they were found to range from 10(5) to 10(6) M-1. The evaluation of the affinity constant of the antibodies produced is always important as a measure of the immunogenicity of an antigen, particularly when synthetic peptides are used as immunogens.

An interactive computer program for the determination of the binding constants of monoclonal antibodies by non-linear regression analysis of radioimmunoassay data

A computer program is presented for non-linear regression analysis of radioimmunoassay data, which allows the determination of the binding parameters of monoclonal antibodies, i.e., affinity constant and number of available binding sites. The program is based on the median method and gives the values of the binding constants and their 95% confidence limits, without the necessity for their preliminary, approximate evaluation. The program may also be used to determine the binding constants for the interaction of receptors with labelled ligands.

Triosephosphate isomerase deficiency: 2 new cases

2 new cases of triosephosphate isomerase (TPI) deficiency associated with severe haemolytic anaemia in 2 unrelated Italian families are described. Only 1 case was extensively investigated. TPI deficiency was detectable in erythrocytes, leucocytes, platelets and plasma. The mutant enzyme showed normal Km for GAP and increased Km for DHAP, with an higher than normal equilibrium constant, decreased thermostability, and abnormal electrophoretic pattern due to the lack of the fastest moving component. The immunological characterization revealed a lower than normal inactivation by specific antiserum, while the double immunodiffusion pattern and the precipitin curve were normal. Lymphocyte, granulocyte and platelet functions were impaired.

Identification of a mixture of two different monoclonal antibodies by nonlinear regression analysis after solid phase radioimmunoassay with labeled antigen

The results of competitive solid phase radioimmunoassay with labeled antigen, when analyzed by nonlinear regression, may reveal the presence of two different monoclonal antibodies, occasionally produced in a hybridoma culture. In fact, a hybridoma-derived antihuman chorionic somatomammotropin antibody prepared in our laboratories showed an unsatisfactory curve fitting when the experimental data were elaborated on the basis of a monoclonal model. The antibody was subjected to recloning, and gave two separate homogeneous monoclonal antibodies with different affinity constants.

Antigenic structure of human chorionic somatomammotropin: four epitopes revealed by monoclonal antibodies

The characterization of epitope specificity of a panel of 15 monoclonal antibodies against human chorionic somatomammotropin (hCS), previously prepared in our laboratory, allowed us to distinguish 4 antigenic determinants on the hCS molecule. Experiments were carried out with competition and sandwich assays. The results allowed us to divide our MAbs into 4 groups, recognizing 4 different epitopes, and to select 4 MAbs each distinguishing a different epitope in order to pursue further studies on the antigenic structure of hCS.

Characterization of monoclonal antibodies against human chorionic somatomammotropin: competitive screening and determination of the affinity constants

A simple screening method has been developed for the characterization of monoclonal antibodies (MAbs) against human chorionic somatomammotropin (hCS) produced in our laboratory. The method is easily adaptable to MAbs against other soluble antigens. Our proposed method allows evaluation of the degree of binding of the antibodies to the antigen, and of cross-reaction with human growth hormone and ovine prolactin. The positive clones have been further characterized by solid-phase radioimmunoassay in order to determine their affinity constants, which ranged from 10(7) to 10(9)/M as determined by non-linear regression analysis.

Identification and synthesis of an antigenic determinant common to human chorionic somatomammotropin and human growth hormone

Human chorionic somatomammotropin (hCS) and human growth hormone (hGH), despite their different biological activities, show a remarkable degree of homology in their primary structure, which explains their immunological cross-reactivity. On the basis of the hydrophilicity profiles, we predicted that the sequence 165-174 would correspond to an antigenic determinant common to both hormones. The sequence 165-174 was synthesized in the solid phase and the ability to bind antibodies to hCS was tested by a radioimmunoassay at each step of the synthesis, without detaching the peptide from the resin. We found that the immunological sequence able to bind antibodies to hCS is that corresponding to 167-174. In similar experiments, we showed that the sequence 166-174 is able to bind antibodies to hGH. In the plaque-forming cell test using the synthetic fragment 166-174 bound to sheep red blood cells, we also observed that the ratio between the number of cells forming antibodies to hCS and to the 166-174 peptide was always between 0.45 and 0.73, thus suggesting that the 166-174 peptide represents a major determinant of hCS.

A new test for the laboratory diagnosis of spherocytosis

A new test for the laboratory diagnosis of spherocytosis, conventionally called 'Pink test', is presented. This test, semi-quantitatively or quantitatively, determines the hemolysis of small blood samples in a solution containing glycerol (135 mmol/l), NaCl (25 mmol/l), NaN3 (1.5 mmol/l), buffered to pH 6.66 with Bis-Tris (70 mmol/l) and HCl. 'Pink test', as well as 'acidified' glycerol lysis test, were positive in 100% of 42 patients suffering from hereditary spherocytosis, and optimally discriminated them from healthy subjects, showing a diagnostic sensitivity greater than 'standard' glycerol lysis test and osmotic fragility in hypotonic saline solutions of fresh or incubated blood. 'Pink test' was also positive in some cases of renal failure, immunohemolytic anemia, chronic hemoproliferative disorders, normal pregnant women, and negative in other microcytic anemias (beta-thalassemia, iron deficiency anemia). The results do not critically depend on pH of the solution (differently from those obtained with 'acidified' glycerol lysis test), and for this reason they show a good reproducibility.

Diagnostic value of the glycerol lysis test

The diagnostic value of the standard glycerol lysis test (GLT) has been evaluated by studying 95 cases of hereditary spherocytosis (HS), 513 beta- and 25 alpha-thalassemia trait (Th) carriers, 170 iron-deficient patients (ID), and 217 patients with miscellaneous hematological conditions. The sensitivity of the test, at 95% specificity, was 97% for beta-Th, 53% for ID, and only 36% for HS, so that the predictive value of a positive result is practically nil for HS, 50% to 85% for Th, and 10% to 35% for ID, depending on the prevalence ratio of the disease in the examined population. The technical variability of GLT, explored by a proper experimental design, was found to be rather high, its main components being repeatability and variability of reagent preparations. The dependence of the results on operators was negligible. It is concluded that GLT is not suitable as a laboratory test for the detection of abnormalities in red cell osmotic fragility because of its very low sensitivity toward increased fragility. For decreased red cell osmotic fragility, the sensitivity of GLT is high; however, it is less valuable than the traditional 0.35% NaCl method as mass screening test for the detection of beta-Th, giving more false positive results.

Simple immunization protocol for high frequency production of soluble antigen-specific hybridomas

We report the immunization protocol used to produce high frequency of specific hybridomas secreting defined antibodies against soluble proteins. The two immunization schemes used consist in 1300 and 115 micrograms of protein distributed over a period of two weeks. The specific efficiency (SE) of positive clones recovered in eleven different fusion experiments ranged between 0.52 and 0.78. These values are referred to hybridomas secreting monoclonal antibodies (MAbs) against soluble proteins such as human chorionic somatomammotropin (hCS), human growth hormone (hGH), and human prostatic acid phosphatase (hPAP). Similar high SE were also recovered by immunizing mice with nonsoluble antigens such as intermediate filaments of cytoskeleton (IF).

Phosphofructokinase (PFK) deficiency due to a catalytically inactive mutant M-type subunit

A case of M-type PFK deficiency due to the synthesis of a structurally abnormal and catalytically inactive M-subunit was reported. PFK activity was reduced (39% of normal) in red cells, normal in leukocytes and platelets, and absent in muscle. The red cell enzyme was not inhibited by antiserum to human muscle PFK and displayed normal biochemical properties (Km for ATP and fructose-6-phosphate, storage stability at +4 degrees C and -80 degrees C, optimum pH, electrophoretic pattern and molecular weight). The complete lack of PFK activity in muscle was confirmed on both histological preparations and muscle extracts. Double immunodiffusion analysis using an antinormal M-PFK serum revealed that the enzyme molecule was present and immunologically identical with normal, although it was catalytically inactive. The muscle abnormality was also confirmed by electromyography, ischemic exercise testing, histochemistry and electron microscopy. Moreover, PFK activity was investigated in myoblast cultures maintained up to 25 days, and it was found to be absent.

Acute hemodynamic effects of Brescia-Cimino arteriovenous fistula for hemodialysis

In ten uremic patients, who were not yet undergoing periodic hemodialysis and in whom we were creating a 1 cm, distal, side-to-side arteriovenous fistula of Brescia-Cimino type for hemodialysis, the acute hemodynamic changes of the systemic and pulmonary circulations were studied immediately after the opening of the fistula. An increase in cardiac output (Q) was observed in one patient, the other patients showing either no change or a slight reduction. In the four patients in whom the Q decreased there was a significant reduction of total blood volume (TBV) and stroke volume (SV) and an increase in systemic vascular resistance (SVR) (p less than 0.05, p less than 0.05, p less than 0.01 respectively). At the level of pulmonary circulation, in these patients a decrease in pulmonary blood volume (PBV) (mean = 20%) and a significant increase in pulmonary vascular resistance (PVR) were also observed. In five patients who had been on chronic hemodialysis and who presented the clinical picture of cardiac failure, the acute hemodynamic changes following temporary closure of the fistula (by a sphygmomanometer) were studied: a significant decrease (p less than 0.05) in Q, TBV and SV was observed. The difference between the two values of Q (i.e. fistula open and closed) was considered to indicate the magnitude of the flow across the fistula.

A modified 'low pH' lignocaine method to isolate human monocytes: a comparison with other separation procedures

A modified 'low pH' lignocaine method for the recovery of human monocytes from untreated plastics is described and compared with other adherence separation procedures, viz. mechanical scraping by a rubber policeman, microexudate-coated plastic method and pretreatment of plastics by the fetal calf serum (FCS). Monocytes separated by each of the above-mentioned techniques carried out in parallel were characterised by morphological and functional criteria: non-specific esterase staining, contamination by T- and B-lymphocytes, viability, adherence, neutral red uptake, phagocytosis of yeast particles, random mobility, chemotaxis, and tumoricidal activity both in the absence and in the presence of interferon and lymphokines. The 'low pH' lignocaine method appears to be a simple and reproducible technique for the isolation of human monocytes. It seem preferable to other adherence procedures inasmuch as it yields viable, pure and functionally intact monocytes without requiring preconditioned plastics.

The first stable variant of erythrocyte glucose-phosphate isomerase associated with severe hemolytic anemia

A new variant of glucosephosphate isomerase (GPI) associated with hemolytic anemia, mental retardation, and muscular hypotonia is described. The defective enzyme showed increased affinity for fructose-6-phosphate (F-6-P), decreased affinity for glucose-6-phosphate (G-6-P) altered electrophoretic and isoelectrofocusing patterns, and shift to the left of the precipitin curve. The enzyme was stable under all the conditions tested (heat, urea, guanidine-HCl, and storage). Optimum pH, Ki for 6-phosphogluconic acid (6-PGA) and for erythrose-4-phosphate (E-4-P), molecular weight, GPI-related antigen concentration, immunodiffusion pattern, and immunoinactivation were in the normal range. This is the first example of the association of a stable mutant GPI with severe hemolytic anemia. Enzyme instability has been present in all previously reported cases.

Metabolic impairment and membrane abnormality in red cells from Huntington's disease

The following aspects have been investigated in 10 patients affected by Huntington's disease )HD): --extensive haematological investigations; --red cell enzyme activities and level of the most important glycolytic intermediate compounds; --protein, lipid and carbohydrate composition of the erythrocyte membrane and membrane polarity; --effects of in vitro aging on red cell membranes. Lack of 4.5 protein band in SDS-PAGE and 14-fold decrease in membrane-bound catalase were found in the in vitro aged red cells from the 10 HD patients examined. Na+ + K+ATPase was slightly higher than normal in all the patients. Red cells from 5 out of 8 patients showed a decrease in reduced glutathione and phosphoenolpyruvate levels and/or an increase in hexokinase, glucose-6-phosphate dehydrogenase, pyruvate kinase and glutathione reductase activities. The haematological investigations, the protein lipid and carbohydrate composition of the fresh red cells, the membrane polypeptide aggregates and the membrane polarity evaluated by microspectrofluorometric analysis were normal.

[Effect of prostaglandins on the cardiovascular system]

Ever since the effect of prostaglandins on vasal tone and cardiac function was discovered, an impressive series of studies has been conducted on their relations with the cardiovascular system. These studies have been extended to the prostaglandin system compounds discovered in more recent times. Of these, particular importance is being attached to prostacycline, though to be implicated in the physiological control of platelet clumping and also in that of renin secretion. Further investigation of the part played by prostacycline and other prostaglandins in cardiovascular disease has given unusually promising interim results.

Cell-mediated immunity in male fertility. Immunological infertility in man

The leukocyte migration inhibition test on agarose was performed on 210 patients with different andrological disorders: oligozoospermia following primarily testicular disorders, oligozoospermia following primarily non testicular disorders and idiopathic oligozoospermia. This test was most applicable in disorders involving testicular damage and in cases of varicocele with altered blood flow. It would appear that cell-mediated immunity is involved in the pathogenesis of the consequences of these disorders.

Quantitative evaluation of the regional left ventricular function in normal subjects by means of cineangiocardiography

A method for analysing left ventricular cineangiograms is described, which not only provides information on the overall ventricular performance, but also evaluates the regional contraction of the left ventricle and the related haemodynamic patterns. This simplified Chapman's method (slice method) makes it possible to calculate the end-diastolic, end-systolic volumes, the stroke volume and the ejection fraction of the zones into which the left ventricle is divided by a longitudinal and by three transverse axes, according to Herman's technique. The hemiventriculograms of 21 normal subjects in the AP projection were evaluated using this method and a 10 of them were also studied in RAO projection. A uniform left ventricular contraction pattern was found for three hemiventricles outlined by the anterolateral, lateral, and postero-medial walls (ejection fraction 71.7 +/- 5.1%, 71.6 +/- 5.9%, 70.4 +/- 5.1%, respectively), the regional and zonal ejection fraction (EFR, EFZ) being similar in both projections. The ejection fraction of the hemiventricle outlined by the septal wall was, however, lower (65.6 +/- 6.0%). The standard zonal function curves of the left ventricle in normal subjects was then calculated on the basis of the results obtained, in order to assess, by comparison, zonal function abnormalities in cardiac patients.