Production and characterization of monoclonal antibodies against bovine pancreatic trypsin inhibitor

Two monoclonal antibodies (MAbs) have been produced, without the use of a supporting carrier, against bovine basic pancreatic trypsin inhibitor (BPTI or aprotinin), a mini-protein composed of 58 amino acids. Both MAbs obtained were found to be IgM. One of them was purified and further characterized. This MAb (ICI) binds to the immunogen with an association constant of 1.6 X 10(6)M-1 at pH 7.4. Competition experiments with trypsin or inactivated trypsin demonstrate that ICI MAb interacts with BPTI at, or near, the proteinase-binding site. ICI MAb binds, with a much lower association constant (approximately 200M-1), to an isoinhibitor (spleen inhibitor II) which differs from BPTI in seven amino-acids; three of these substitutions are at the active site, in the contact area with the proteinase.

A simple method for increasing hapten immunogenicity by a specific structural modification of the carrier

A simple procedure to bind haptens, drugs or peptides selectively through their amino or carboxylic group to a spacer arm modified non-immunogenic polypeptide is described. Gelatin, a well known non-immunogenic carrier, was modified by blocking its amino groups. Spacer arms with primary amino groups such as beta-alanine or ethylenediamine were conjugated to this protein by carbodiimide resulting in spacer modified gelatin. These modified polypeptides were tested for their ability to selectively bind haptens through their amino or carboxylic groups. Three probes were used and the results obtained confirm the hypothesis. Three conjugates obtained were further used to induce an immune response in mice. Enhancement of the immunogenicity of these spacer-arm supported haptens was observed. Overall, this study provides a rational approach to the production of well defined antigens using a simple conjugation technique.

[Determination of the range of physiologic variation of the electrical axes using P, QRS, and T waves in pregnancy]

Since functional overload in pregnancy frequently induces the appearance of symptoms that could arouse suspicion of myocardiopathy, it is important to analyse and characterize all electrocardiographic modifications during a healthy subject's pregnancy. Variations of the mean electrical axis (A) of P, QRS and T waves were evaluated in 52 healthy volunteers, 17-37 years, during pregnancy. The A values were measured, in the frontal plane, at the end of both I and III quarter of pregnancy, using a method of scalar determination. The As in I and III quarters was compared with those observed in the post-partum (at 5th day) and statistical evaluations were performed (Student t-test for paired observations). In the I quarter the mean A was 40 +/- 3 degrees for P, 40 +/- 16 degrees for QRS and 32.5 +/- 9 degrees for T wave, whereas in the III quarter the mean A changed to 37 +/- 2 degrees for P, 34 +/- 18 degrees for QRS and 31 +/- 9 degrees for T. During pregnancy, all mean As significantly diverted to the left side, AP about 3 degrees, AQRS about 6 degrees and AT about 1.5 degrees. These results were also confirmed by analysis of A frequency distribution histograms. In the post-partum (5th day) the A resumed basal values (I quarter's values). These results show: i) the physiological range of AP, AQRS and AT, during pregnancy; ii) left deviation of all three As at the end of III quarter. It is possible to conclude that variation over this range, particularly for QRS, could give evidence of the onset of cardiopathy.

Production and characterization of monoclonal antibodies against DNA single ring diamines adducts

The synthetic conjugate of the genotoxic compound 2,4 diaminotoluene (2,4 DAT) with gelatin (2,4 DAT-GEL) was employed to elicit specific antibodies directed against a restricted class of aromatic diamines. Using this immunogen, mouse monoclonal antibodies (MAbs) have been produced. These MAbs have been characterized and used in ELISA to detect 2,4 DAT covalently linked to biopolymers. The MAbs could bind to different synthetic 2,4 DAT-biopolymer adducts as well as to DNA from rats treated in vivo with the aromatic diamine, but they did not react with gelatin or biopolymers alone. The use of these MAbs has been investigated in order to develop a highly sensitive test to detect adducts of this genotoxic compound with nuclear DNA.

Combined effects of immunity and antitumor drugs against cancer. II. In vitro studies with cis-diamminedichloroplatinum in a human leukemia system

Human K562 leukemic cells were exposed in vitro to cis-diamminedichloroplatinum (DDP) followed by addition of intact or irradiated mononuclear cells (MNC) obtained from peripheral blood of normal donors. tumor inhibition provoked by DDP was significantly enhanced by normal MNC, but not by irradiated cells at the effector: leukemic cell ratio of 2:1. In contrast MNC alone did not show appreciable effects on K562 cells. The NK activity of MNC was also inhibited by exposure to gamma rays. The combined effects of DDP + MNC do not appear to be due to increased susceptibility of DDP-pretreated K562 cells to NK-mediated cytolysis. Actually leukemic cells treated with 10 micrograms/ml of DDP and cultured for 48 h at 37 degrees C, showed decline of susceptibility to the cytotoxic effects of MNC. These studies suggest that natural immunity could be of potential value in the clinical use of DDP.

Effect of the 5HT2 antagonist ritanserin on food intake and on 5HT-induced anorexia in the rat

The present study investigated the effect on the rat's eating behavior of the new selective 5HT2 antagonist ritanserin. The results obtained indicate that: single subcutaneous (SC) injection of ritanserin, at doses between 0.1 and 1 mg/kg b.wt., neither elicits food intake in sated rats, nor increases the intake induced by food deprivation; subchronic SC treatment (15 days) with 0.1 mg/kg does not increase food intake nor body weight gain; subchronic SC treatment with high doses, 1 or 10 mg/kg, produces small and transient increases in food intake without affecting body weight gain. When ritanserin was tested for its ability to block the anorectic effect of exogenous 5HT, it inhibited the effect of intraperitoneal (IP) 5HT, but proved to be completely inactive versus the effect of 5HT injected into the hypothalamic paraventricular nucleus, which is highly sensitive to this effect of 5HT. This last finding suggests that the anorectic action of central endogenous 5HT is also not blocked by ritanserin, thus proposing a reasonable explanation for the absence of orexigenic effect following its administration. Moreover, it suggests that in rats the hypothalamic receptors mediating the effect of 5HT on eating behavior are different from the 5HT2 of the frontal cortex which have been shown to be completely blocked by ritanserin under the experimental conditions employed in our study.

Ritanserin, a serotonin-S2 receptor antagonist, does not prevent 5-hydroxytryptophan-induced beta-EP, beta-LPH and cortisol secretion

Ritanserin, a new serotonin antagonist selective upon S2 receptor subclass is available. Thus, in order to better define the positive control of serotoninergic pathway on proopiomelanocortin (POMC)-related peptide release, a group of 7 healthy male volunteers has been submitted to a 5-hydroxytryptophane (5-OH-TP) test (200 mg p.o.) before and after 4 days Ritanserin pretreatment. Plasma beta-endorphin (beta-EP), beta-lipotropin (beta-LPH) and cortisol levels were measured hourly for 4 h after each 5-OH-TP loading. Hormonal levels were measured by specific RIAs on extracted (cortisol) and chromatographed (beta-EP and beta-LPH) plasma samples. Basal plasma concentrations of the three hormones were unchanged by Ritanserin pretreatment. Similarly, the integrated areas of beta-LPH, beta-EP and cortisol release in response to 5-OH-TP remained unaffected by the receptor blockade. These data confirm that serotonin-acting drugs are able to stimulate POMC-related peptide release and indicate that such interaction is not mediated through S2 receptor subclass.

Evidence for serotonin-S2 receptor involvement in analgesia in humans

The possible analgesic activity of ritanserin (a new very selective and potent serotonin-S2 antagonist) was studied (double-blind) in humans. A significant increase in nociceptive flexion reflex threshold and subjective pain threshold was observed after five days of treatment, while treatment with placebo did not induce any change. The effects of ritanserin were not reversed by either naloxone or saline (double-blind) administration. Our data suggest a possible role of serotonin-S2 receptors in analgesia.

Influence of interferon on the functional expression of natural killer target structures of murine lymphoma cells

Murine lymphoma cells (YAC-1), induced by Moloney leukemia virus, nontreated (YAC) or pretreated in vitro with interferon (YAC-IF), were tested for their susceptibility to natural killer (NK)-mediated cytolysis. In line with previous reports YAC-IF were less susceptible to NK lysis than YAC cells. In cold competition assay, YAC-IF inhibited cytotoxicity to a lesser extent than YAC lymphoma when labeled target YAC cells were used. However, when radioactive YAC-IF cells were used as targets, cold competition attained with both YAC and YAC-IF was essentially the same. Furthermore, effector splenocytes, depleted of NK effector cells through immunoabsorption on YAC monolayer, were inactive against both YAC and YAC-IF targets. On the other hand, effector lymphocytes, absorbed on YAC-IF monolayer, retained NK activity against YAC cells but not against YAC-IF targets. These results are compatible with the hypothesis that interferon (IF) modulates negatively a subset of "interferon-susceptible" (IFS) NK target structure(s) (TS) of YAC cells, which would then express membrane determinants not functionally present on YAC-IF cells. On the other hand YAC and YAC-IF cells share "interferon-resistant" (IFR) TS not affected by pretreatment with IF. In order to test whether IFS X TS and IFR X TS are present on the same cell or clonally distributed, YAC cells were cloned and tested for NK susceptibility following IF pretreatment. The results did not support the hypothesis of a clonal distribution of both IFS X TS and IFR X TS since IF pretreatment of all clones, obtained by limiting dilution, resulted in a net impairment of target susceptibility to NK effector cells.

Life-span, tumor incidence, and natural killer cell activity in mice selected for high or low antibody responsiveness

Biozzi mice selected for high (H) or low (L) antibody responsiveness to natural antigens have been followed for their entire life-span to examine their pathology at death. As previously found in selection I, shorter life-span and higher lymphoma incidence were observed in L responder mice than in H responder mice selected for antibody responsiveness to sheep red blood cells (selection II). In mice selected for antibody responsiveness to Salmonella flagellar antigens (selection III), similar life-span and similar lymphoma incidence were found in H and L responder mice. Natural killer (NK) cell activity, as assessed in spleen cells from young mice, was lower in L than in H responder mice of selection I but higher in L than in H responder mice of both selections II and III. All these results indicate that longevity and lymphoma incidence at death are independent of NK cell activity in mice selected for H or L antibody responsiveness to natural antigens. Furthermore, genetic selection for antibody responsiveness does not always appear to influence life-span and lymphoma incidence.