Home  About us  Contact
 

Malaria Antigen (malaria + antigen)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

Phenotypic analysis of human peripheral blood regulatory T cells (CD4+FOXP3+CD127lo/,) ex vivo and after in vitro restimulation with malaria antigens

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2010
Olivia C. Finney
Abstract Regulatory T cells (Treg) play crucial roles in regulating autoimmune responses and immunity to tumors and infectious diseases. However, numerous subpopulations of Treg are now being described and the utility of various Treg markers is being reassessed. Here we report the results of a detailed phenotypic comparison of two supposedly regulatory human T-cell populations, namely CD4+FOXP3+ T cells and CD4+CD25hi T cells. We find that CD4+FOXP3+ cells are extremely heterogeneous with respect to CD25 expression and that FOXP3+ and CD25hi CD4+ T cells differ in their expression of chemokine receptors (CCR), CD95 and Bcl-2, suggestive of distinct migration characteristics and susceptibility to apoptosis. Further, we propose that CD25 expression should be regarded as an activation marker rather than as a defining marker of Treg. Lastly, CD4+FOXP3+ T cells activated in vitro with malaria antigen expressed the highest levels of CCR4 and CD95, and the lowest levels of CCR7, indicating that they are most likely generated from effector memory cells during an immune response and rapidly succumb to apoptosis at the end of the response. [source]

Homeostatic regulation of T effector to Treg ratios in an area of seasonal malaria transmission

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2009
Olivia C. Finney
Abstract An important aspect of clinical immunity to malaria is the ability to down-regulate inflammatory responses, once parasitaemia is under control, in order to avoid immune-mediated pathology. The role of classical (CD4+CD25+CD127lo/,FOXP3+) Treg in this process, however, remains controversial. Thus, we have characterized the frequency, phenotype and function of Treg populations, over time, in healthy individuals in The Gambia. We observed that both the percentage and the absolute number of CD4+FOXP3+CD127lo/, T cells were higher among individuals living in a rural village with highly seasonal malaria transmission than among individuals living in an urban area where malaria rarely occurs. These CD4+FOXP3+CD127lo/, T cells exhibited an effector memory and apoptosis-prone phenotype and suppressed cytokine production in response to malaria antigen. Cells from individuals exposed to malaria expressed significantly higher levels of mRNA for forkhead box P3 and T-box 21 (T-BET) at the end of the malaria transmission season than at the end of the non-transmission season. Importantly, the ratio of T-BET to forkhead box P3 was remarkably consistent between populations and over time, indicating that in healthy individuals, a transient increase in Th1 responses during the malaria transmission season is balanced by a commensurate Treg response, ensuring that immune homeostasis is maintained. [source]

Differential immunoglobulin E and cytokine responses in BALB/c and C57Bl/6 mice during repeated infections with blood-stage Plasmodium chabaudi malaria

PARASITE IMMUNOLOGY, Issue 4 2000
Helena Helmby
Repeated blood-stage Plasmodium chabaudi chabaudi AS challenge infections in BALB/c and C57Bl/6 mice result in increased serum immunoglobulin (Ig) E levels and splenic cytokine production. The genetic background of the host influences both the cytokine response as well as the development of IgE antibodies. BALB/c mice showed high interleukin (IL)-4 secretion from splenocytes after in-vitro stimulation with malaria antigen after repeated P. chabaudi challenges and this was closely followed by higher levels of total IgE. Despite slightly elevated serum IgE levels, splenocytes from C57Bl/6 mice did not secrete any detectable IL-4 but produced interferon (IFN)-, in response to malaria antigen-stimulation in vitro. These data suggest that induction of IgE antibodies during murine malaria infection is genetically regulated. [source]

Phenotypic analysis of human peripheral blood regulatory T cells (CD4+FOXP3+CD127lo/,) ex vivo and after in vitro restimulation with malaria antigens

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2010
Olivia C. Finney
Abstract Regulatory T cells (Treg) play crucial roles in regulating autoimmune responses and immunity to tumors and infectious diseases. However, numerous subpopulations of Treg are now being described and the utility of various Treg markers is being reassessed. Here we report the results of a detailed phenotypic comparison of two supposedly regulatory human T-cell populations, namely CD4+FOXP3+ T cells and CD4+CD25hi T cells. We find that CD4+FOXP3+ cells are extremely heterogeneous with respect to CD25 expression and that FOXP3+ and CD25hi CD4+ T cells differ in their expression of chemokine receptors (CCR), CD95 and Bcl-2, suggestive of distinct migration characteristics and susceptibility to apoptosis. Further, we propose that CD25 expression should be regarded as an activation marker rather than as a defining marker of Treg. Lastly, CD4+FOXP3+ T cells activated in vitro with malaria antigen expressed the highest levels of CCR4 and CD95, and the lowest levels of CCR7, indicating that they are most likely generated from effector memory cells during an immune response and rapidly succumb to apoptosis at the end of the response. [source]

Activation by malaria antigens renders mononuclear cells susceptible to HIV infection and re-activates replication of endogenous HIV in cells from HIV-infected adults

PARASITE IMMUNOLOGY, Issue 5 2004
K. Froebel
SUMMARY We have tested the hypothesis that activation of T cells by exposure to malaria antigens facilitates both de novo HIV infection and viral reactivation and replication. PBMC from malaria-naïve HIV-uninfected European donors could be productively infected with HIV following in vitro stimulation with a lysate of Plasmodium falciparum schizonts and PBMC from malaria-naïve and malaria-exposed (semi-immune) HIV-positive adults were induced to produce higher levels of virus after stimulation with the same malaria extract. These findings suggest that effective malaria control measures might con-tribute to reducing the spread of HIV and extending the life span of HIV-infected individuals living in malaria endemic areas. [source]