Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

PBL from individuals with no history of malaria exposure, as well as cord blood lymphocytes, were tested for proliferation to T cell epitopes from the malaria circumsporozoite proteins of Plasmodium falciparum and Plasmodium vivax. Cells from many individuals proliferated in response to these peptides, but for two peptides (P. vivax317-336 and P. falciparum CS331-350) the response rate ranged from 64 to 93%, with the specific stimulation indices reaching as high as 38. The phenotype of the cells responding to PfCS331-350 was predominantly CD4+,CD8-,CD45Ra+,CD45Ro-, which was the inverse of the phenotype of the cells responding to tetanus toxoid with respect to CD45 isoforms. T cell clones from different individuals specific for PfCS331-350 were restricted by at least four different HLA-DR molecules and there was no evidence that the peptide was a "superantigen." Overlapping peptides were used to demonstrate that clones had different fine specificities although the peptide specificities of the DR4-restricted and DR11-restricted clones were similar. Although the individuals tested here have had no history of malaria exposure, these data demonstrate that they have T cells specific for malaria sequences present in high frequency that proliferate as intensely as some memory responses. Although one clone from an individual with a history of BCG vaccination did react strongly with PPD, the phenotype of these cells suggests that they are not classical memory cells for a cross-reactive recall Ag. Such cells may affect the induction or expression of malaria immunity.
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PMID:Promiscuous malaria peptide epitope stimulates CD45Ra T cells from peripheral blood of nonexposed donors. 137 May 23

Plasma and peripheral blood mononuclear cells (PBMC) were obtained from P. falciparum-infected individuals with and without the sickle cell trait at diagnosis and 7 days after treatment. HbAA and HbAS patients were compared for levels of plasma soluble IL-2 receptors (IL-2R) and the in vitro cellular reactivity to affinity-purified soluble P. falciparum antigens (SPAg), PPD and phytohaemagglutinin (PHA). At diagnosis, HbAS patients with clinical disease had lower plasma-soluble IL-2R levels and parasite counts than the corresponding HbAA patients, whereas HbAS and HbAA patients with asymptomatic infections had comparable soluble IL-2R levels and parasite counts. PBMC from HbAS patients had higher proliferation and IFN-gamma production in response to SPAg than PBMC from HbAA patients. The difference in the lymphoproliferative responses to SPAg between the two groups was evident in patients with asymptomatic infections. In all patients, the clinical severity, the soluble IL-2R levels and the parasite counts were directly related. The former two were inversely related to the proliferative responses to SPAg. After treatment, all the studied parameters were comparable in the two groups. The study indicates that during P. falciparum infection, HbAS compared with HbAA patients had lower in vivo cellular activation and higher in vitro cellular reactivity in response to soluble malaria antigens.
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PMID:Modulation of the cellular immune response during Plasmodium falciparum infections in sickle cell trait individuals. 156 96

In this longitudinal study peripheral blood mononuclear cells (PBMC) were obtained before and during the malaria season from healthy HbAA and HbAS children. Cells were compared for proliferation in response to stimulation by soluble Plasmodium falciparum antigens (SPAg) or purified derivative of tuberculin (PPD). The lymphoproliferative responses to SPAg of the paired PBMC samples showed 2 distinct seasonal changes in relation to the haemoglobin phenotype. In HbAA children, the lymphoproliferative responses to SPAg were suppressed during the malaria season. In contrast, they were enhanced in HbAS children during the malaria season. No distinct seasonal change in the response to PPD was found in relation to the haemoglobin phenotype. The study points to the role of the sickle cell trait in modulating the cellular immune responses to falciparum malaria.
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PMID:Seasonal changes in cell mediated immune responses to soluble Plasmodium falciparum antigens in children with haemoglobin AA and haemoglobin AS. 156 93

Sixteen patients suffering from acute Plasmodium falciparum malaria were studied. All were residents of an area of unstable malaria-transmission in Eastern Sudan. Blood-samples were drawn at diagnosis, and 7 and 30 days later. Blood-samples from thirteen donors, drawn outside the malaria transmission season 5 months prior to the attack, were included in the study. Lymphoproliferative responsiveness to purified soluble malarial antigens and to the unrelated antigen PPD was lost during the acute phase of the disease in most donors, but was regained during convalescence, except in four donors recrudescing or reinfected by day 30. In contrast to the suppression of antigenic responses, cellular responses to phytohaemagglutinin (PHA) remained virtually unaffected. All donors showed elevated plasma-levels of soluble IL-2 receptor during the acute phase of the disease which normalized during convalescence. Five donors examined by fluorescence-activated cell sorting (FACS) showed no increase in surface expression of IL-2 receptor on peripheral lymphocytes. The data indicate that acute P. falciparum malaria causes a depletion of antigen-reactive T-cells from the peripheral circulation, probably due to homing of this cell-population to lymphoid tissues. It was also found that acute-phase plasma was suppressive to PPD-induced proliferative responses, indicating an additional suppressive mechanism operating in vivo.
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PMID:Loss of cellular immune reactivity during acute Plasmodium falciparum malaria. 193 Nov 34

Children with malarial infection, due to P. Vivax and P. falciparum, were tested for cell mediated immunity (CMI) by lymphocyte proliferative response to mitogens PHA (phytohaemagglutinin) and PWM (poke weed mitogen) and antigen PPD (purified protein derivative). This was done during the period of parasitemia and after treatment, and compared to 19 normal matched controls. There was no significant difference between the patients and the control group with regard to PHA (patients 57.4 +/- 50.5; controls 61.3 +/- 54.9); PWM (patients 27.4 +/- 19.9, controls 29.9 +/- 24.5); PPD (patients 2.2 +/- 1.2, controls 1.9 +/- 1.4). There was also no significant difference in the lymphocyte responses during the period of parasitemia and after treatment. Hence, there does not seem to be any depression of CMI as shown by lymphocyte proliferative responses during childhood malaria.
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PMID:Cell mediated immunity in childhood malaria. 224 18

To determine the possible differences in the immune response to Plasmodium falciparum between sickle-cell trait (Hb AS) and normal haemoglobin (Hb AA) individuals, we examined 35 Hb AS and 24 Hb AA subjects matched for age and microenvironment. Their age was 2-55 years and all lived in a malaria endemic area 300 km south of Khartoum. Antibodies to ring-infected erythrocyte surface antigen (Pf155/RESA) and to circumsporozoite (CS) protein (anti-NANP40) indicated equal exposure to falciparum malaria. Peripheral blood mononuclear cells (BMNCs) from 20/35 (57%) Hb AS subjects compared with 10/24 (42%) Hb AA subjects, responded to affinity-purified P. falciparum soluble antigens (SPAg). Of those responding to SPAg, 9 (26%) Hb AS subjects and only two (8%) Hb AA subjects had high responses. The mean proliferative response to SPAg of BMNCs from Hb AS individuals was significantly higher than in Hb AA individuals (P less than 0.025). Responses of BMNCs to PPD and PHA were also higher among Hb AS individuals and correlated positively with responses to SPAg. These findings support the hypotheses that the sickle-cell trait protects individuals from P. falciparum infections, at least in part, by modulating the immune response.
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PMID:Cell-mediated immune responses to Plasmodium falciparum purified soluble antigens in sickle-cell trait subjects. 228 54

Mononuclear cells (MNC) isolated from malaria immune donors and from donors never exposed to malaria were stimulated in vitro with soluble purified Plasmodium falciparum antigens (SPag) or PPD. After 7 days of culture the proliferative response and the cytotoxic activity against the natural killer cell (NK cell) sensitive cell line, K562, were measured. It was found that SPag stimulation enhanced cytotoxic activity of MNC from donors whose lymphocytes exhibited a strong proliferative response to the antigen. MNC with low proliferative responsiveness showed increased cytotoxic activity if the MNC were preincubated with interleukin 2 (IL-2) for one hour before the start of the cytotoxic assay. SPag activation did not enhance the cytotoxic activity of MNC which did not respond to the antigen in the proliferation assay, and preincubation of these cells with IL-2 did not increase the activity. PPD stimulation enhanced the cytotoxic activity and induced strong proliferative responses in all MNC preparations. The role of NK cells in the protection against malaria is unknown, but they play a role in the protection against virus infection and in the immune surveillance against cancer. Our findings indicate that malaria antigens either directly or through the activation of immunoregulatory cells enhance the NK cell activity.
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PMID:Enhancement of human natural cytotoxicity by Plasmodium falciparum antigen activated lymphocytes. 244 9

Malaria infection has been shown to induce alterations in immune reactivity. This report describes the effect of serum obtained from Plasmodium falciparum infected patients on in vitro proliferation of human blood mononuclear cells (BMNC) isolated from healthy individuals. Serum obtained before initiation of treatment suppressed the in vitro lymphocyte proliferative response to both Plasmodium-derived antigens and an unrelated antigen (PPD-tuberculin). The suppressive effect was lost if the serum was incubated at 56 degrees C for 30 min, and the effect was not HLA-restricted since the inhibition was seen on both autologous and heterologous BMNC. The degree of suppression was not correlated to the duration of the disease, the degree of parasitemia, or the use of chemoprophylaxis. Sera from 7 patients before and from 3 patients 30 days after initiation of treatment were pooled and fractionated. It was found that the strongest suppressive activity was in the serum fraction containing molecules from 30-100 kD.
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PMID:Inhibition of human lymphocyte proliferative response by serum from Plasmodium falciparum infected patients. 332 60

The first 100 Indochinese refugee patients screened at Oakland (Calif) Children's Hospital had a remarkably high incidence of treatable infectious and parasitic diseases. The PPD skin tests were positive in 28%, and stool parasites were present in 65%. There were wide differences among the various ethnic groups in prevalence of stool parasites, anemia, and hemoglobin E trait, with a higher rate among Cambodians accounting for these differences. There were also differences in stool parasite patterns when the refugees were separated by ethnic origin. Cambodians had predominantly hookworm and Strongyloides, Laotians harbored hookworm and Trichuris, and Vietnamese were infested with Trichuris and Giardia. Malaria. Pott's disease, and congenital syphilis were among the uncommonly encountered diseases. Results of screening will vary with ethnic origin, but health screening has a high yield for all Indochinese refugees.
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PMID:Health screening of Indochinese refugee children. 710 21

Immune responses of 97 Gambian women and their neonates were studied. New methods distinguished between active and previous placental malaria, were used to examine relationships between maternal malaria and neonatal immune responses. Many placentas (61%) had active or previous malarial infection. Maternal and cord malarial IgG levels correlated (P < 0.001). Malarial IgG was raised in cord blood in active placental malaria; IgM was not detected. Mean lymphoproliferation and the proportion of responders to soluble P. falciparum antigens (F32) and conserved regions of p190 expressed on trophozoites and schizonts (190L and 190N) were higher in neonates than mothers. There was no clear relationship between maternal malaria and neonatal mean lymphoproliferation to malarial antigens, although fewer neonates responded when mothers were actively infected. Matched maternal and neonatal lymphoproliferation responses did not correlate. However, first born neonatal lymphoproliferation to PPD and malarial antigens appeared lower than other neonates, in agreement with lower lymphoproliferation in primigravidae compared with multigravidae. Also in common with mothers, autologous plasma suppressed neonatal lymphoproliferation to PPD and malarial antigens, suggesting common immunoregulation. Higher cortisol or other circulating factors in first pregnancies may be implicated. The relevance of cell-mediated malarial immune responses detected at birth remains to be established.
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PMID:Relationships between maternal malaria and malarial immune responses in mothers and neonates. 773 30


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