Effect of bacterial polysaccharide on the primary and secondary immunologic response following immunization with sheep erythrocytes

The effect of typhoid bacterial polysaccharide on the primary and secondary immune response to SRBS was studied. The polysaccharide was shown to have both stimulating and depressive effect on the population of antibody-producing cells. This effect depended on the time and the number of polysaccharide injections. Thus, a single polysaccharide injection made on the day preceding immunization resulted in the maximum stimulation in the system of IgM- and IgG-producing cells, while the maximum depression of these cells could be observed after 2 polysaccharide injections: on the day preceding immunization and on the day of immunization. In the secondary immune response considerable stimulation of the populations of antibody-producing cells was observed after polysaccharide injections made on days 2 and 3 after reimmunization.     

Passive immunization with neutralizing antibodies interrupts the mouse mammary tumor virus life cycle

Mouse mammary tumor virus (MMTV) infects the host via mucosal surfaces and exploits the host immune system for systemic spread and chronic infection. We have tested a neutralizing rat monoclonal antibody specific for the retroviral envelope glycoprotein gp52 for its efficiency in preventing acute and chronic mucosal and systemic infection. The antibody completely inhibits the superantigen response and chronic viral infection following systemic or nasal infection. Surprisingly however, the antibody only partially inhibits the early infection of antigen-presenting cells in the draining lymph node. Despite this initially inefficient protection from infection, superantigen-specific B- and T-cell responses and systemic viral spread are abolished, leading to complete clearance of the retroviral infection and hence interruption of the viral life cycle. In conclusion, systemic neutralizing monoclonal antibodies can provide an efficient protection against chronic retroviral amplification and persistence.     

The effect of primary and secondary immunization on the lymphoid tissues of the carp, Cyprinus carpio L

Mirror carp immunized with human gamma globulin (HGG) in Freund's complete adjuvant (FCA) show a proliferative response involving cells whose cytoplasm stains deep red with methyl green-pyronin (pyroninophilic cells). This response occurs particularly in the haemopoietic parenchyma of the pronephros and mesonephros. It peaks at week 3, with the formation of clusters of pyroninophilic cells in the pronephros. Immunization with Aeromonas salmonicida elicited a less intense pyroninophilic response but caused a larger increase in pigment-containing cells. After a secondary immunization with HGG in FCA, a distinct response was observed in the spleen: Pyroninophilic cells collected within the ellipsoid sheaths in large numbers and formed nodules. The reticulum of such nodules acquired spherical proportions and resembled the white pulp reticulum of the tetrapod spleen. The roles of such pyroninophilic cells and the possibility that aggregations of them may be functionally analogous to homoiotherm germinal centres are discussed.     

Facing two T cell epitopes: a degree of randomness in the primary response is lost upon secondary immunization

We have analyzed the hierarchy of epitope-specific T cell populations during a primary and a secondary CD8 T cell response. MHC-peptide tetramers were used to track the in vivo kinetics of expansion of T cell populations specific for two Kd-restricted epitopes simultaneously presented by a murine tumor cell following primary or recall immunizations. Individual syngeneic mice generated remarkably different primary CTL responses, as reflected by up to 60-fold differences in the relative contribution of each peptide-specific T cell population to the overall response. In these primary immunizations, the CTL dominance was not dictated by the respective abundance of the presented epitopes. In sharp contrast, the secondary response was systematically associated with a selective expansion of the same epitope-specific population both in vitro and in vivo. In vitro experiments indicated that the extent of expansion of each epitope-specific memory population is modulated by the epitope density. We conclude that, at least for this set of epitopes, the CTL hierarchy is not controlled by the same parameters in a primary vs a secondary response.     

The influence of mRNA primary and secondary structure on human IFN-gamma gene expression in E. coli.

Parameters influencing the efficiency of expression of the human immune interferon (IFN-gamma) gene in E. coli were studied by comparing a series of eight in vitro-derived gene variants. These contained all possible combinations of silent mutations in the first three codons of the mature IFN-gamma polypeptide coding sequence. Expression levels varied up to 50-fold among the different constructions. Comparison of messenger RNA secondary structure models for each variant suggested that the presence of stem-loop structures blocking the translation initiation signals could drastically decrease the efficiency of IFN-gamma synthesis. With variants displaying no stable mRNA secondary structure in the region, a C----U transition at position +11 after the AUG resulted in a 5-fold increase in expression indicating that RNA primary structure also plays an important role in expression. In addition we demonstrate that, in this system, a spacing of 8 nucleotides between the Shine-Dalgarno region and AUG was optimal for gene expression and that the steady-state production level of IFN-gamma rose exponentially with increasing rate of synthesis.     

Passive immunization of mice with monoclonal antibodies to glycoprotein gB of herpes simplex virus

To investigate the protective ability of monoclonal antibodies (MCAs) to viral glycoprotein in herpes simplex virus (HSV) infection, athymic nude mice were inoculated intracutaneously with HSV type-1 (HSV-1) in the midflank. Three hours after inoculation, one group of mice was passively immunized with one of a series of MCAs to glycoprotein gB of HSV-1, and a control group of mice was given phosphate buffered saline alone. The control mice died within 16 days after infection, whereas the mice passively immunized with any of the MCA showed suppressed development of skin lesions. Three of six mice given MCA failed to develop any visible lesions and no HSV could be isolated from the lumbar dorsal root ganglia of these mice 60 days after the challenge. BALB/c mice were also protected from infection with HSV type 2 by passive immunization with MCA to HSV-1 gB.     

Nonlabeled secondary antibodies augment/maintain the binding of primary, specific antibodies to cell membrane antigens.

BACKGROUND: In studies on surface membrane antigen expression using immunofluorescence techniques, it is commonly observed that direct staining gives weaker signals than the signals following indirect staining with fluorochrome-conjugated secondary antibodies. This is most marked when cells have also been permeabilized in order to stain intracellular protein. The commonly accepted explanation for this observation is that fluorochrome-conjugated secondary antibodies bind to a higher number of binding sites on the primary antibody, as compared to the binding of conjugated primary antibodies to the membrane antigens. Another hypothesis might be that the antibody/antibody complexes formed on the membranes when using the indirect technique may have an augmented ability to bind the membrane epitopes. The present study was performed in order to check this hypothesis. MATERIALS AND METHODS: Peripheral blood mononuclear cells were stained with fluorochrome-conjugated anti-CD antibodies directly without or with a second-step application of nonconjugated goat anti-mouse IgG antibodies, followed by different fixation and permeabilization methods. The cells were analyzed by flow cytometry. RESULTS: A second-step application of nonconjugated goat anti-mouse IgG antibodies following direct staining with fluorochrome-conjugated anti-CD antibodies gave a significant increase in membrane antigen expression on permeabilized cells as compared to direct staining alone. The secondary antibody must be bivalent, since whole IgG or F(ab')(2) fragments of the goat anti-mouse antibodies showed effects, while Fab fragments did not. CONCLUSIONS: Nonlabeled secondary antibodies are able to influence the binding of primary, specific antibodies to cell membrane antigens on cells treated with permeabilizing agents necessary for staining intracellular proteins. The improved membrane antigen expression seems to be due to the formation of a network of primary and secondary antibodies on the cell surface, with increased ability for maintaining binding to CD antigens.     

Interaction of allogeneic lymphocytes and precursor cells during the primary and secondary immune response]

A mixture of lymph node cells from CBA mice and spleen cells from C57Bl/6J mice stimulated by the cheep erythrocytes fro the first or second time was transplanted in the lethally irradiated mice (CBA X C57Bl/6j)Fl. The interaction of allogenic cells during the secondary immune response was accompanied by the complete inactivation of antibody producents. Under the ratio of interacting cell elements 1 : 1-1 : 2, 93-96% of precursor cells and 98% of antibody forming cells were inactivated. Under the ratio 1 : 5, the index of inactivation of precursor cells fell down to 35%. During the primary response, under the ratio 1 : 1, only 20-48% of precursor cells and 68% of antibody forming cells were inactivated. Under the ratio 1 : 2, no inactivation of precursor cells was observed and, under the ratio 1 : 10, the antibody formation was stimulated. Following the delayed by 1-3 days transplantation of CBA lymphocytes, the cooperative effect was registered with respect to the spleen cells from C57Bl/6J mice stimulated by the erythrocytes for the first time. The interaction of allogenic cells resulted in the 3-4-fold increase in the number of antibody forming cells.     

Passive immunization for the treatment and prevention of HIV infection.

Passive immunization using serum or immunoglobulin preparations has been used in the prophylaxis and treatment of many bacterial and viral diseases. Preliminary attempts to use these methods to prevent HIV infection in chimpanzees have been promising. With the identification of polyclonal and monoclonal antibodies with protective activity against HIV in in vitro systems, the possibility of using these reagents in vivo takes on new relevance. The potential and problems of using passively administered anti-HIV antibodies for HIV prophylaxis and treatment are discussed, as well as the relative merits of polyclonal versus monoclonal reagents.     

The influence of straining maneuvers on the pressor response during isometric exercise

Experiments were performed to determine to what extent increments in esophageal and abdominal pressure would have on arterial blood pressure during fatiguing isometric exercise. Arterial blood pressure was measured during handgrip and leg isometric exercise performed with both a free and occluded circulation to active muscles. Handgrip contractions were exerted at 33 and 70% MVC (maximum voluntary contraction) by 4 volunteers in a sitting position and calf muscle contractions at 50 and 70% MVC with the subjects in a kneeling position. Esophageal pressure measured at the peak of inspirations did not change during either handgrip or leg contractions but peak expiratory pressures increased progressively during both handgrip and leg contractions as fatigue occurred. These increments were independent of the tensions of the isometric contractions exerted. Intra-abdominal pressures measured at the peak of either inspiration or expiration did not change during inspiration with handgrip contractions but increased during expiration. During leg exercise, intraabdominal pressures increased during both inspiration and expiration, reaching peak levels at fatigue. The arterial blood pressure also reached peak levels at fatigue, independent of circulatory occlusion and tension exerted, averaging 18.5-20 kPa (140-150 mm Hg) for both handgrip and leg contractions. While blood pressure returned to resting levels following exercise with a free circulation, it declined by only 2.7-3.8 kPa after leg and handgrip exercise, respectively, during circulatory occlusion. These results indicate that straining maneuvers contribute 3.5 to 7.8 kPa to the change in blood pressure depending on body position.