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Results for “Immunologic Memory”

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At least 649 records · Page 36Linked to original sources
PubMed1986

Effect of cyclosporin A on immunity to Listeria monocytogenes.

The effect of the immunosuppressive drug cyclosporin A (CS-A) on immunity to the facultative intracellular bacterium Listeria monocytogenes was investigated in unprimed and primed mice. Different treatment protocols were followed to evaluate the time dependence of CS-A-mediated immune suppression and the effect of CS-A on immunological memory to L. monocytogenes. The effect of CS-A was observed only during and after activation of T cell-mediated immunity, whereas early resistance exerted by macrophages assessed 6 and 70 min after challenge remained unaffected. CS-A suppressed efficient elimination of L. monocytogenes even when given after day 3 of a primary infection. This contrasts with findings in other models, including viral infections, where CS-A must be administered very early in an immune response to suppress it. CS-A suppressed antibacterial resistance in mice primed at various times before challenge; suppression of protection was time dependent and was virtually complete in livers, whereas CS-A-resistant memory persisted in spleens for up to 10 months.

Animals↗
PubMed2002

Can nonliving nasal vaccines be made to work?

Nasal vaccines consisting of nonliving particulate formulations can induce immune responses of importance for protection against infection. The most promising results have been obtained with vaccines against influenza, pertussis and group B meningococcal disease. So far, however, the results do not challenge the standing of corresponding injectable vaccines, although results of experiments in animals do indicate that effective nonliving nasal vaccines may soon be developed. This will depend on refined immunization schedules to benefit from immunological memory and on formulations to make the vaccines more accessible to the immune system by way of mucosal adjuvants or immune modulators.

Adjuvants, Immunologic↗
PubMed1982

Alloantigen-induced suppressor- and memory cells in chronic lymphocytic leukemia.

T cell function was evaluated in patients with B cell type of chronic lymphocytic leukemia (CLL). Unseparated peripheral blood lymphocytes (PBL) and T cells from CLL patients stimulated in a primary allogeneic MLR were able to inhibit significantly a second MLR between the original responder (CLL) and stimulator (normal PBL) cell donors. Furthermore, it is shown the T lymphocytes from patients with CLL develop immunologic memory during the course of a primary MLR as evidenced by an enhanced response in secondary MLR. These results are discussed with respect to recently described imbalances of T cell subpopulations in CLL.

B-Lymphocytes↗
PubMed1977

Primary tumor immunity in nude mice.

Tumor implants grew better in radiated or in newborn nu/nu mice than in adult nu/nu controls when, and only when, the tumors were demonstrably immunogenic in normal mice. This result suggests primary immunity. No evidence of immunological memory was found by immunization-challenge type experiments in the nude mice.

Animals↗
PubMed1999

Persistence of lymphocytic choriomeningitis virus at very low levels in immune mice.

Lymphocytic choriomeningitis virus (LCMV), strain WE, is a non-cytopathic RNA virus that is highly adapted to its natural host, the mouse. Acute infection of adult mice leads to generalized virus spread, followed by cytotoxic T lymphocyte-mediated virus clearance below the detection levels of conventional assays within 2-3 weeks. Indirect evidence had suggested that virus or viral antigen might persist in the immune mouse. Here we demonstrate LCMV-WE persistence at low levels after infection with 10(2) or 10(6) plaque-forming units, shown as viral genome, viral antigen, and replicative virus using sensitive in vitro and in vivo assays. The finding that LCMV-WE persists in the face of apparently intact immune responses resembles the situation in some viral (hepatitis B and C, HIV) and bacterial (tuberculosis, leprosy) infections in humans; the results are relevant to the understanding not only of other murine and human persistent viral infections but also of protective immunological memory by "infection immunity."

Animals↗
PubMed2005

Cationic liposomes containing mycobacterial lipids: a new powerful Th1 adjuvant system.

The immunostimulation provided by the mycobacterial cell wall has been exploited for many decades, e.g., in Freund's complete adjuvant. Recently, the underlying mechanism behind this adjuvant activity, including Toll receptor signaling, has begun to be unraveled, confirming the potential of mycobacterial constituents to act as adjuvants. In this study, the immunostimulatory properties of a Mycobacterium bovis BCG lipid extract were tested for their adjuvant activity. Administration of the lipids in dimethyl dioctadecyl ammonium bromide-based cationic liposomes induced a powerful Th1 response characterized by markedly elevated antigen-specific immunoglobulin G2a (IgG2a) isotype antibodies and substantial production of gamma interferon. The adjuvant formulation (designated mycosomes) elicited high levels of gamma interferon both in C57BL/6 as well as in Th2-prone BALB/c mice. Furthermore, the mycosomes induced immune responses to protein antigens from several sources including Mycobacterium tuberculosis, Chlamydia muridarum, and tetanus toxoid. In a tuberculosis challenge model, the mycosomes combined with the Ag85B-ESAT-6 fusion protein were demonstrated to have a unique ability to maintain sustained immunological memory at a level superior to live BCG.

Adjuvants, Immunologic↗
PubMed1978

Effects of the B-cell activators lipid A and dextran sulphate on the antibody response to sheep red blood cells in piglets.

The in vivo effects of Lipid A and dextran sulphate on the antibody response to the thymus-dependent antigen SRBC in piglets are reported. No alteration of the low primary antibody response was observed with any of the B-cell activators. However, both substances induced an increase in antibody titre after secondary challenge with the antigen, which was shown to be of the IgG class. An activation of immunological memory in the absence of primary antibody response is suggested.

Animals↗
PubMed1982

[Nonspecific Shigella suppression of delayed hypersensitivity].

Experimental study in mice has revealed that live virulent shigellae, in contrast to killed ones, suppress the secondary immune response to guinea pig splenocytes, manifested as delayed type hypersensitivity. This suppression is caused by disturbances in the process of the realization of the existing immunological memory: avirulent shigellae have been proved to cause no such effect.

Animals↗
PubMed2006

Therapeutic immunization for HIV.

Vaccines have entered into human clinical trials against infectious diseases and as therapies against cancer. The HIV virus establishes a latent infection at a very early stage and the T cell memory of the infected patient is rapidly destroyed. However, results of immunotherapy after DNA and protein immunization show that vaccine-induced immune responses might be present for a long period of time. Patients subjected to therapeutic immunization appear to do well, and to have a small immunological advantage, which, however, will have to be improved. The vaccine therapy should start early, while adequate reservoirs of appropriate T helper cells are available and still inducible. The DNA vaccines induce a relatively long-lived immunological memory, and gene-based immunization is effective in inducing cytotoxic CD8(+) T cells and CD4+ helper cells. Protein vaccines, on the other hand, primarily give T cell help. It thus appears that DNA and protein approaches to HIV immunization complement each other. A surprisingly broad reactivity to peptides from different subtypes of HIV was identified in individuals infected with several subtypes of HIV.

AIDS Vaccines↗
PubMed2004

Immune responses to Bacillus anthracis protective antigen in patients with bioterrorism-related cutaneous or inhalation anthrax.

Anti-protective antigen (PA) immunoglobulin (Ig) G, toxin neutralization, and PA-specific IgG memory B cell responses were studied in patients with bioterrorism-related cutaneous or inhalation anthrax and in a patient with laboratory-acquired cutaneous anthrax. Responses were determined for >1 year after the onset of symptoms. Eleven days after the onset of symptoms (15 days after likely exposure), anti-PA IgG was detected in 16 of 17 patients with confirmed or suspected clinical anthrax who were tested. Anti-PA IgG remained detectable 8-16 months after the onset of symptoms in all 6 survivors of inhalation anthrax and in 7 of 11 survivors of cutaneous anthrax who were tested. Anti-PA IgG levels and serum toxin neutralizing activity were strongly associated (R2=0.83). PA-specific IgG memory B cells were detectable in all 6 survivors of inhalation anthrax but in only 2 of 7 patients with cutaneous anthrax who were tested. Anti-PA IgG is an important diagnostic marker of anthrax, a predictor of serum anti-toxin activity, and a marker of immunological memory against anthrax.

Anthrax↗
PubMed1995

Renal transplantation to sensitized patients: decreased graft survival probability associated with a positive historical crossmatch.

Sensitized patients may reject renal transplants at a tempo or with a force dictated by their previous exposure to alloantigen. The patient's pretransplant alloimmunization status is usually assessed by the measurement of panel reactive antibodies (PRAs) and by the crossmatch. The test results using current patient's sera are of considerable predictive value. In contrast, the relevance of historical sera is much debated. To further investigate the correlation of PRA and crossmatch with clinical outcome, 852 cadaveric kidney transplants were evaluated. As expected, graft survival was significantly longer (p = 0.01;logrank test) in nonimmunized patients (n = 516) compared to immunized patients with more than 10% PRA (n = 297). Patients with persistently positive PRAs (n = 171) were then compared to patients with positive historical but negative current PRAs (n = 126). Interestingly, their graft survival was practically identical. Finally, transplants across a positive historical T cell crossmatch (n = 39) had a significantly reduced graft survival (p = 0.015) compared to transplants in immunized patients (n = 297, all T cell crossmatch negative). Thus, this study confirms the increased risk in sensitized patients and shows that the antigen specific immunological memory is of clinical relevance even if donor specific antibodies are not detectable in current sera.

Adult↗
PubMed2006

The effect of T cell independent and cross-reactive antigen on the immune response to pneumococcal conjugate vaccination.

The effect of priming with various antigens on subsequent vaccination with the pneumococcal conjugate vaccine (CPV) was determined using BALB/c mice. Priming with pneumococcal polysaccharide or cross-reactive polysaccharide did not inhibit the IgG response to CPV immunization. Additionally, live intranasal colonization by Streptococcus pneumoniae or cross-reactive organism resulted in higher IgG responses to CPV. These results suggest that colonization elicits immunological memory capable of boosting the immune response to CPV.

Animals↗
PubMed1990

Fecal IgA antibody responses after oral poliovirus vaccination in infants and elder children.

We investigated fecal IgA antibody responses after oral polyvalent poliovirus vaccination. Infants were given vaccines twice with an interval of 6 weeks. Specific IgA antibodies in the feces were determined by enzyme-linked immunosorbent assay, and viruses were isolated in tissue cultures. We found that, after the first vaccination, antibody responses seemed to be elicited only against the serotypes of isolated viruses. After the second vaccination, however, antibodies were detected to all three serotypes with higher titers, suggesting that the first vaccination induced the immunologic memory. The IgA antibodies had virus-neutralizing activity, and existed in the feces as both intact 11S and fragmented 4S molecules. Next, children were given the third vaccination 3 or 9 years later. Fecal IgA antibody responses were found to be poorer in elder children, while they responded with high serum neutralization titers. The secretory IgA memory seemed to last much shorter the serum IgG memory.

Adolescent↗
PubMed1980

Antitoxic cholera immunity in mice: influence of antigen deposition on antitoxin-containing cells and protective immunity in different parts of the intestine.

The importance of the mode of antigen presentation (intravenous, oral, or enteral restricted to the lower ileum) in the development of a local immune response and immunological memory for such a response in different parts of the intestine was studied in mice. Cholera toxin was used as antigen and the immune response was assayed by determining both the number of specific antitoxin-containing cells in the lamina propria and protection against experimental cholera. The results showed that all of these routes of antigen presentation could induce significant memory along the entire small intestine. In contrast, the actual production of antitoxin-containing cells or protective immune response elicited by booster immunization was restricted to those parts of the intestine that were directly exposed to antigen; i.e., lower ileum boosting resulted in immunity in the distal ileum but not in the proximal jejunum, whereas oral or intravenous boosting gave a response in both jejunum and ileum. Protection correlated closely with the number of antitoxin-containing cells in the lamina propria (correlation coefficient, 0.88); >/=4,000 antitoxin-containing cells per mm(3) conferred solid immunity to cholera toxin-induced diarrhea. The total number of immunoglobulin-containing cells in intestines was not significantly influenced by the specific immunizations. There were four times as many of these cells in the upper jejunum (167,000 cells per mm(3)) as in the lower ileum, but the proportions of immunoglobulin A-containing cells (80 to 85%), immunoglobulin M-containing cells (14 to 20%), and immunoglobulin G-containing cells (0.4 to 0.9%) were similar in various parts of the intestine. The results indicate a differential dependence on local tissue antigen for the intestinal antibody-secreting cells and their memory cell precursors.

Animals↗
PubMed1996

Stress-induced effects on integral immune components involved in herpes simplex virus (HSV)-specific memory cytotoxic T lymphocyte activation.

We have previously shown that restraint stress suppresses the activation of a polyclonal population of herpes simplex virus (HSV)-specific memory cytotoxic T lymphocytes (CTLm) to the lytic phenotype. We have extended these findings by demonstrating that this suppression occurs in two distinct HSV-specific CTLm populations that are generated in C57BL/6 mice in response to HSV infection and that recognize distinct epitopes expressed early in the HSV infection cycle. Moreover, these CTLm exhibited different levels of susceptibility to stress-induced suppression of activation. To elucidate the mechanisms responsible for this suppression, we have examined the effect of restraint on immunological components that are necessary for CTLm activation. We demonstrated that the expression of the T cell receptor (TCR), IL-2 receptor (IL-2R), and other accessory molecules involved in T cell activation were similar on CD8(+) T cell populations from both control and restrained groups of mice. However, splenic lymphoid cells from restrained mice generated significantly lower levels of IL-2, IL-4, IL-6, and gamma interferon (IFN-gamma) than did those cells from control, nonrestrained mice. The reduced ability to activate HSV-specific CTLm from mice subjected to restraint could be overcome by increasing the cell density and, thus, the lymphokine concentrations in these cultures. Overall, these findings suggest that restraint stress does not affect the inherent ability of an HSV-specific CTLm to be activated to the lytic phenotype; rather, the availability of lymphokines necessary to drive the activation process may be the limiting factor as to whether or not CTLm activation occurs. This stress-induced suppression of lymphokine production may not only play a role in inhibiting HSV-specific CTL activation but may also contribute to a diminution in the responsiveness and function of other components of immunological memory that are dependent on the presence of lymphokines.

Animals↗
PubMed1994

Isoforms of the transmembrane tyrosine phosphatase CD45 differentially affect T cell recognition.

Activation of T cells has been shown to require CD45. CD45 is expressed on T cells as distinct isoforms and these isoforms are expressed differentially on subsets of CD4 T cells. We have generated T cell lines expressing a T cell receptor (TCR) of known specificity, with or without CD4, and examined the effect of different CD45 isoforms on stimulation through the antigen receptor. We find that isoforms differ in their ability to participate in antigen recognition, with the null isoform that is predominantly found on memory CD4 T cells being the most effective. The ability of the CD4 T cells being the most effective. The ability of the CD45 ectodomain to differentially affect sensitivity to specific ligands represents a novel way of regulating the efficacy of signaling through a receptor without altering its specificity. It may play a crucial role both in immunological memory and during intrathymic maturation of T cells.

Animals↗
PubMed1990

A simple model for the immune network.

In this note I present a simple model for the idiotypic network among antibodies and study its relevance for the maintenance of immunological memory; in particular, the memory capacity of such a model is studied. Some of the similarities with the spin glass model and with neural networks are discussed.

Animals↗
PubMed1998

Antibody avidity as a surrogate marker of successful priming by Haemophilus influenzae type b conjugate vaccines following infant immunization.

Evaluation of the new generation of conjugate vaccines is hampered by the absence of reliable surrogate markers of immunologic memory. Memory responses are characterized by rapid production of relatively high-avidity antibody; thus, a solid-phase ELISA was adapted for the measurement of anti-Haemophilus influenzae type b (Hib) IgG avidity. In a cohort of infants vaccinated at 2, 3, and 4 months of age with Hib conjugate vaccines, avidity increased in the period following vaccination, while antibody titer fell. After a booster dose at 1 year of age, both antibody titer and avidity increased. In a cohort with anti-Hib IgG <1.0 microg/mL following primary immunization, antibody avidity after booster was low, indicating an absence of priming. Antibody avidity may help distinguish, in persons with low antibody titers, between those who are primed for memory and those who are not.

Antibodies, Bacterial↗