Malaria treated with emetine or metronidazole.
Explore the source record for details and available documents.
Emetine↗
Biomedical subjects
R F James
Publications and source records attributed to R F James.
Augmentation of cell-mediated responses in vitro by a monoclonal anti-helper factor antibody.
Previous studies have shown that monoclonal antibody AF3.44.4 has specificity for a constant region determinant on mouse antigen-specific helper factors and that it also binds to cultured T cells with functional helper cell characteristics. The antibody synergizes with antigen to enhance in vitro antibody responses; here we demonstrate that it will also enhance cell-mediated responses in vitro such as in the generation of proliferating cells in mixed lymphocyte responses and in the generation of specific killer cells in cytotoxic T lymphocyte cultures. The mechanism of AF3.44.4-generated enhancement was investigated. Increased levels of the lymphokines IL-2 and BCDF were detected in supernatants of AF3.44.4-treated cultures but the antibody itself could not replace interleukin-2 (IL-2), and would not stimulate primed cells in the absence of antigen. This type of monoclonal antibody which augments immunological responses in an antigen-dependent fashion may provide a new class of immunostimulant and a new approach to augmenting the responses of weak immunogens.
Animals↗
A monoclonal antibody against antigen-specific helper factor augments T-cell help.
Antigen-specific molecules, commonly termed 'factors', have been shown to be released from helper and suppressor T cells. These factors mimic the activity of the cells that secrete them and there is much speculation about the relationship of antigen-specific factors to T-cell receptors for antigen. We have raised a variety of antisera in rabbits which were shown to react against conserved 'constant' determinants on either helper or suppressor factors independently of antigenic specificity or mouse strain of origin of the factor. In contrast, syngeneic mouse antisera were found to react with 'variable' factor determinants in an antigen-specific and mouse strain-dependent manner. These antisera thus define two regions on factor molecules, one 'variable' (related to antigen specificity) and the other 'constant' (related to function). However, potential contaminants in these antisera have limited their usefulness. Thus, we are now generating monoclonal antibodies against T-cell factors and report here the properties of a monoclonal antibody (AF3.44.4) which reacts with antigen-specific helper factors. This antibody also binds to helper T cells and, in the presence of antigen, augments helper cell induction in vitro, which, in turn, leads to enhanced antibody production in vitro. These characteristics suggest that AF3.44.4 recognizes a determinant shared by helper factor and the antigen receptor on helper T cells.
Animals↗
Transfection as an approach to understanding membrane glycoproteins.
Explore the source record for details and available documents.
Animals↗
Maternal plasma HbF levels in pregnancy.
Serial maternal serum hemoglobin F (HbF) levels were measured by radioimmunoassay in 23 normal pregnancies. The maternal HbF fraction remains within the normal range during the first trimester (mean + 2 S.D. = 0.15 + 0.13). After 15 weeks gestation, maternal HbF levels rise in some, but not all, pregnancies. In about 30% of the cases the HbF fraction remains within the range seen in adult men and non-pregnant women. Irregular rises in HbF were found in other pregnancies studied serially. The maternal HbF fraction may be an indicator of transplacental hemorrhage.
Female↗
Expression of murine H-2Kb histocompatibility antigen in cells transformed with cloned H-2 genes.
Cosmids containing H-2 histocompatibility antigen genes of the H-2b haplotype have been isolated. One of these genes expresses a 45,000 molecular weight protein, indistinguishable from H-2Kb when introduced into mouse L cells. These H-2Kb transformed L cells can be killed by allospecific anti-H-2Kb cytotoxic T cells. Moreover, when infected with influenza virus, they can be killed by an H-2Kb-restricted, influenza virus-specific cytotoxic T cell line. These results show that expression of the H-2Kb gene product on the L-cell surface is sufficient to make it a target for specific T-cell killing.
Animals↗
Structure of antigen-specific suppressor factors: current views.
Explore the source record for details and available documents.
Animals↗
The isolation of the gamma subunit of fetal hemoglocin (HbF) and its use in a radioimmunoassay for HbF.
A method is described for the purification, from fetal hemoglobin (HbF), of the fetal specific globin chain (gamma chain) in its native state. In the absence of alpha chain (the globin chain common to all adult human hemoglobins) gamma chain, when used as an immunogen, is able to express its unique antigenicity. Here, a specific, high titer antiserum raised against gamma chain has been used to establish a sensitive radioimmunoassay for HbF. This approach may be applicable to the measurement of other normal and abnormal hemoglobins.
Absorption↗
Identification of a high molecular weight enzyme component in crude C histolyticum collagenase that is essential for the appropriate disaggregation of the pig and human pancreas.
Explore the source record for details and available documents.
Animals↗
The kinetics of SCID-hu reconstitution: a comparison between human splenocytes and peripheral blood leucocytes.
Although preliminary studies have shown that the severely combined immunodeficient (SCID)-hu mouse can reject allo tissue, they have also highlighted the current limitations of the SCID-hu model. These limitations are the need for unambiguous identification of human cells in the SCID mouse and the variability of the reconstitution efficiency. The purpose of this study was to follow the kinetics of SCID-hu reconstitution, comparing human splenocytes (SC) with peripheral blood leucocytes (PBL) to ascertain whether the presence of post-thymic progenitor cells in SC improved the efficiency of reconstitution. SCID mice were injected intraperitoneally with 5 x 10(7) PBL from five normal volunteers, and with 5 x 10(7) SC from 5 organ donor spleens. Two animals per donor were culled on weeks 2, 4, 8, and 16, and the frequency and level of SCID-hu reconstitution assessed by flow cytometric analysis of peritoneal cells and splenic leucocytes. Total serum immunoglobulin levels were measured fortnightly to follow the kinetics of B lymphocyte reconstitution. A marked degree of variability was seen in the frequency and extent of reconstitution, regardless of the source of lymphocytes. However, in comparison with PBL, human SC, predominantly T cells, were able to persist and increase in number, migrating from the peritoneal cavity to secondary lymphoid tissue. We conclude that human SC provide a better source of human lymphoid cells for SCID reconstitution than PBL.
Animals↗
Pancreatic islet purification using bovine serum albumin: the importance of density gradient temperature and osmolality.
Euro-Ficoll and bovine serum albumin (BSA) are two of the most commonly used density gradient media for the purification of pancreatic islets. Euro-Ficoll is based upon Euro-Collins, a cold storage medium, and must, therefore, be used at 4 degrees C. The ionic composition of BSA, however, is likely to contribute to hypothermic cellular swelling, and this may influence the efficiency of islet purification using this medium at 4 degrees C. Experience in this laboratory also suggested that batch-to-batch variation in islet purity using BSA was related to differences in BSA osmolality. The aim of this study was to assess the effect of gradient medium temperature and osmolality on the purification of human and porcine islets using BSA. Pancreata were collagenase-digested, and islets were purified on continuous linear density gradients of BSA. The distribution of insulin and amylase in each gradient was assayed, and used to calculate the median density of islets and exocrine tissue, and the efficiency of islet purification (% amylase contamination at a fixed insulin yield), using: 1) gradient osmolalities of 300, 400, and 500 mOsm/kg H2O (seven porcine pancreata), and 2) gradients at 4 degrees C and at 22 degrees C (eight human and seven porcine pancreata). Increase in density gradient osmolality produced increases in porcine exocrine tissue density which exceeded changes in islet density, resulting in improved islet purity, maximal at a BSA osmolality of 400 mOsm/kg H2O. For human pancreata there was no significant change in pancreatic tissue densities nor islet purity with temperature.(ABSTRACT TRUNCATED AT 400 WORDS)
Adolescent↗
The potential contribution of rejection to survival of transplanted human islets.
Clinical islet transplantation is potentially the treatment of choice for people with type I diabetes. Rates of insulin independence in islet transplant recipients are disappointingly low, and the relative contribution of the rejection response compared with the loss of islet function is still unclear. We have compared the mixed lymphocyte islet coculture (MLIC) with the mixed lymphocyte acinar cell coculture (MLAC) and the mixed lymphocyte response (MLR) as in vitro models of allograft rejection to MHC and tissue-specific antigens expressed by human islets and acinar cells. The reduced number of MHC class II antigen-positive cells in islets and acinar tissue compared to those in the stimulator lymphocyte population of the MLR, correlated with a reduced proliferative response in the MLIC and MLAC. Enhancement of MHC class II antigen expression by islets using TNFalpha and IFNgamma did not increase their stimulatory capacity in the islet cocultures, which may have been due to a corresponding absence of B7 expression. The lack of T cell proliferation to acinar cells despite cytokine-induced enhancement of MHC class II expression and detectable B7 expression appeared to be due to the inhibitory effect of exocrine enzymes on lymphocyte proliferation. In conclusion, we suggest that a rejection response to islets and acinar tissue is possible due to the accompanying MHC class II-positive cells and that, in this model, islet and acinar-specific antigens do not significantly contribute to that response. Acinar cells may have the potential to stimulate lymphocytes directly, but this was not evident by proliferation in the MLAC. Rejection appears to contribute to the low survival rate of human islet allografts, but it is unlikely that this is the sole explanation, and other factors should be considered.
Cells, Cultured↗
The effect of capsule composition on the biocompatibility of alginate-poly-l-lysine capsules.
The encapsulation of islets of Langerhans in alginate-poly-l-lysine has been proposed as a method for the immunoprotection of transplanted islets. Although several capsule compositions have been reported, there has been no published study concerning the effect of capsule composition on the severity of the foreign body reaction. Empty capsules were prepared from high mannuronic acid alginate and were coated with: (1) poly-l-lysine alone, (2) poly-l-lysine plus high guluronic acid alginate, or (3) poly-l-lysine plus high mannuronic acid alginate. The capsules were placed in the renal subcapsular space or the peritoneal cavity, and retrieved after three weeks of histological examination. The recipients were WAG/01a, nude (athymic), diabetic BB, and non-diabetes prone BB rats. The severity of reaction to the capsules was determined by measuring the thickness of the pericapsular cell infiltrate or by a scoring system. The severity of the reaction to the capsules was strain-dependent in both the renal and peritoneal sites, with the BB and nude rats displaying the most severe responses. The degree of response was not affected by capsule composition in the renal subcapsular space, but in the peritoneum, the high mannuronic acid alginate capsules provoked the weakest response, and this type of capsule will be used for future transplantation work. The infiltrating cells were characterised by immunohistochemistry and electron microscopy and found to be mostly fibroblasts and macrophages.
Alginates↗