Adding heat to the live-high train-low altitude model: a practical insight from professional football.

OBJECTIVES: To examine with a parallel group study design the performance and physiological responses to a 14-day off-season 'live high-train low in the heat' training camp in elite football players. METHODS: Seventeen professional Australian Rules Football players participated in outdoor football-specific skills (32 ± 1°C, 11.5 h) and indoor strength (23 ± 1°C, 9.3 h) sessions and slept (12 nights) and cycled indoors (4.3 h) in either normal air (NORM, n=8) or normobaric hypoxia (14 ± 1 h/day, FiO2 15.2-14.3%, corresponding to a simulated altitude of 2500-3000 m, hypoxic (HYP), n=9). They completed the Yo-Yo Intermittent Recovery level 2 (Yo-YoIR2) in temperate conditions (23 ± 1°C, normal air) precamp (Pre) and postcamp (Post). Plasma volume (PV) and haemoglobin mass (Hb(mass)) were measured at similar times and 4 weeks postcamp (4WPost). Sweat sodium concentration ((Na(+))(sweat)) was measured Pre and Post during a heat-response test (44°C). RESULTS: Both groups showed very large improvements in Yo-YoIR2 at Post (+44%; 90% CL 38, 50), with no between-group differences in the changes (-1%; -9, 9). Postcamp, large changes in PV (+5.6%; -1.8, 5.6) and (Na(+))sweat (-29%; -37, -19) were observed in both groups, while Hb(mass) only moderately increased in HYP (+2.6%; 0.5, 4.5). At 4WPost, there was a likely slightly greater increase in Hb(mass) (+4.6%; 0.0, 9.3) and PV (+6%; -5, 18, unclear) in HYP than in NORM. CONCLUSIONS: The combination of heat and hypoxic exposure during sleep/training might offer a promising 'conditioning cocktail' in team sports.

Monitoring fitness, fatigue and running performance during a pre-season training camp in elite football players.

OBJECTIVES: To examine the usefulness of selected physiological and perceptual measures to monitor fitness, fatigue and running performance during a pre-season, 2-week training camp in eighteen professional Australian Rules Football players (21.9±2.0 years). DESIGN: Observational. METHODS: Training load, perceived ratings of wellness (e.g., fatigue, sleep quality) and salivary cortisol were collected daily. Submaximal exercise heart rate (HRex) and a vagal-related heart rate variability index (LnSD1) were also collected at the start of each training session. Yo-Yo Intermittent Recovery level 2 test (Yo-YoIR2, assessed pre-, mid- and post-camp, temperate conditions) and high-speed running distance during standardized drills (HSR, >14.4 km h(-1), 4 times throughout, outdoor) were used as performance measures. RESULTS: There were significant (P<0.001 for all) day-to-day variations in training load (coefficient of variation, CV: 66%), wellness measures (6-18%), HRex (3.3%), LnSD1 (19.0%), but not cortisol (20.0%, P=0.60). While the overall wellness (+0.06, 90% CL (-0.14; 0.02) AU day(-1)) did not change substantially throughout the camp, HRex decreased (-0.51 (-0.58; -0.45)% day(-1)), and cortisol (+0.31 (0.06; 0.57) nmol L(-1)day(-1)), LnSD1 (+0.1 (0.04; 0.06) ms day(-1)), Yo-YoIR2 performance (+23.7 (20.8; 26.6) m day(-1), P<0.001), and HSR (+4.1 (1.5; 6.6) m day(-1), P<0.001) increased. Day-to-day ΔHRex (r=0.80, 90% CL (0.75; 0.85)), ΔLnSD1 (0.51 (r=0.40; 0.62)) and all wellness measures (0.28 (-0.39; -0.17)

TACI-Ig prevents the development of airway hyperresponsiveness in a murine model of asthma.

BACKGROUND: Increased levels of serum IgE are associated with greater asthma prevalence and disease severity. IgE depletion using an anti-IgE monoclonal antibody has met with success in the treatment of moderate-to-severe and severe persistent allergic asthma. OBJECTIVE: To test whether B cell-targeted therapy is a more effective treatment for airway hyperresponsiveness (AHR) in a murine model compared with IgE-depletion. METHODS: We delivered soluble mTACI-Ig, a receptor for the B cell survival factors BLyS (B Lymphocyte Stimulator) and APRIL (A PRoliferation-Inducing Ligand), or anti-IgE to allergen-sensitized mice before airway challenge with allergen. RESULTS: mTACI-Ig treatment reduced circulating mature B cell levels in the blood, while anti-IgE treatment had no effect on B cell counts. Both mTACI-Ig and anti-IgE decreased the levels of total and allergen-specific IgE in the serum. Histopathologic analysis of lungs showed a reduction in disease severity scores for both treatment groups, but results were more pronounced in mTACI-Ig-treated mice. Neutrophil and eosinophil numbers in the bronchoalveolar lavage (BAL) were significantly reduced following mTACI-Ig treatment, but not after anti-IgE delivery. BLyS and APRIL blockade also resulted in a significant decrease in IL-4 and eotaxin mRNA and IL-4 and KC protein levels in total lung homogenates and BAL fluid, respectively. Finally, mTACI-Ig treatment was more effective than anti-IgE treatment in reducing AHR to inhaled antigen. CONCLUSIONS: Our data demonstrate that delivery of mTACI-Ig is a more effective treatment than anti-IgE mAb in a murine model of AHR.

A MAGE-3 peptide presented by HLA-B44 is also recognized by cytolytic T lymphocytes on HLA-B18.

Antigens encoded by MAGE genes are of particular interest for cancer immunotherapy because of their tumoral specificity and because they are shared by many tumors. Antigenic peptide MEVDPIGHLY, which is encoded by MAGE-3 and is known to be presented by human leukocyte antigen (HLA)-B44, is currently being used in therapeutic vaccination trials. We report here that a cytolytic T lymphocyte (CTL) clone, which is restricted by HLA-B*1801, recognizes the same peptide and, importantly, lyzes HLA-B18 tumor cells expressing MAGE-3. These results imply that the use of peptide MEVDPIGHLY can now be extended to HLA-B18 patients. We also provide evidence that, under limiting amounts of protein MAGE-3, HLA B*1801 and B*4403 compete for binding to the peptide.

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.

Identification of a second major tumor-specific antigen recognized by CTLs on mouse mastocytoma P815.

Murine mastocytoma P815 induces CTL responses against at least four distinct Ags (AB, C, D, and E). Recent studies have shown that the main component of the CTL response against the P815 tumor is targeted against Ags P815AB and P815E. The gene P1A has been well characterized. It encodes the P815AB Ag in the form of a nonameric peptide containing two epitopes, P815A and P815B, which are recognized by different CTLs. Here, we report the identification of the P815E Ag. Using a cDNA library derived from tumor P815, we identified the gene coding for P815E. We also characterized the antigenic peptide that anti-P815E CTLs recognize on the MHC class I molecule H-2Kd. The P815E Ag results from a mutation within an ubiquitously expressed gene encoding methionine sulfoxide reductase, an enzyme that is believed to be important in the protection of proteins against the by-products of aerobic metabolism. Surprisingly, immunizing mice i.p. with syngeneic tumor cells (L1210) that were constructed to express B7-1 and P815E did not induce resistance against live P815, even though a strong anti-P815E CTL response was observed with splenocytes from immunized animals.

The shared tumor-specific antigen encoded by mouse gene P1A is a target not only for cytolytic T lymphocytes but also for tumor rejection.

A number of human tumor antigens have been characterized recently using cytolytic T lymphocytes (CTL) as screening tools. Some of them are encoded by MAGE-type genes, which are silent in normal tissues except in male germ cells, but are activated in a variety of tumors. These tumor-specific shared antigens appear to be promising targets for cancer immunotherapy. However, the choice of these antigens as targets has been questioned because of the lack of direct evidence that in vivo responses against such antigens can lead to tumor rejection. The antigen encoded by the mouse gene P1A represents the only available animal model system for MAGE-type tumor antigens. We show here that mice immunized by injection of L1210 leukemia cells expressing P1A and B7-1 (L1210.P1A.B7-1) are efficiently protected against a challenge with a lethal dose of mastocytoma P815 tumor cells, which express P1A. Mice immunized with L1210 cells expressing B7-1 but not P1A were not protected. Furthermore, we observed that P1A-transgenic mice, which are tolerant to P1A, were not protected after immunization with L1210.P1A.B7-1. These results demonstrate that the immune response to P1A is the major component of the tumor rejection response observed in normal mice, and support the use of tumor-specific shared antigens as targets for the immunotherapy of human cancer.

Fine epitope specificity of antibodies to region II of the Plasmodium vivax circumsporozoite protein correlates with ability to bind recombinant protein and sporozoites.

Recent work has suggested that important B- and T-cell epitopes on the circumsporozoite protein (CSP) of Plasmodium vivax lie external to the major repeat regions of the protein. We have studied two naturally exposed human populations (Caucasian and Papua New Guineans) and determined the antibody response to yeast-derived recombinant CSPs, overlapping synthetic peptides spanning amino acids 76 348 of the Belem P. vivax CSP and overlapping peptides representing the variant repeats of the VK247 strain of P. vivax. We have demonstrated that the P. vivax CSP-specific antibody response is directed towards areas within the repeat region as well as areas external to this; but the dominant epitopes recognized by the two populations studied, were distinct. One epitope, lying external to the repeats and recognized by both populations, partially overlaps an area of the protein referred to as region II-plus. Sera from malaria-exposed Papua New Guineans and Thais contained antibodies to this epitope (V22, single letter amino acid sequence TCGVGVRVRRRVNAANKKPE) which were capable of recognizing sporozoites, as determined by quantitative inhibition IFA. Seventeen percent of PNG sera had antibodies to this peptide compared with 33% who had antibodies to the central repeats of the protein. Immunization of mice with recombinant CSP did not induce antibodies to V22. However, immunization with overlapping peptide epitopes representing this region (V21 or V22) induced specific antibodies but only two sera recognized both V21 and V22 and, by inference, the overlapping peptide sequence (TCGVGVRVRR). Antibodies in these two sera could bind recombinant CSP in ELISA; however, in contrast, nine sera which recognized either V21 or V22 alone did not bind CSP. Only one of two sera containing antibodies recognizing CSP stained P. vivax sporozoites. This serum also recognized an epitope dependent upon two amino acids aminoterminal to V22. These data suggest that the fine specificity of antibodies is a critical determinant for binding to both recCSP and sporozoites.

Human T-cell responses to malaria: mostly forgotten or committed to memory?

T cells have been implicated in both malaria immunity and malaria disease and factors controlling the maintenance of T-cell responses over time may alter the clinical outcome o f infection. Michael Good and Janine Bilsborough have compared the T-cell responses to epitopes from the Plasmodium vivax and P. falciparum circumsporozoite proteins and here discuss the issue of T-cell memory as it applies to malaria.

Identification of Caucasian CD4 T cell epitopes on the circumsporozoite protein of Plasmodium vivax. T cell memory.

We have identified a population of Caucasians with a defined past history of infection with Plasmodium vivax malaria. Using purified synthetic peptides overlapping the sequence of the circumsporozoite protein, we determined the percentage of individuals whose T cells proliferated or secreted IFN-gamma in response to peptide stimulation, for both this population and a population of nonmalaria-exposed control individuals. A number of peptides were recognized by both groups, but 11 peptides were uniquely recognized by the exposed population, and thus represented malaria-specific T cell epitopes. CD4 T cells were found to be responsible for the proliferative response. Humans last exposed to vivax sporozoites as long ago as 49 yr responded as well or better to these malaria-specific epitopes as individuals exposed within the previous month. Since such malaria-induced memory response may not be a feature of Plasmodium falciparum infections, and since P. falciparum does not have a persisting hypnozoite stage, our data argue that the persistence of T cell memory to vivax epitopes may result from antigenic persistence in the liver.

'Original antigenic sin', T cell memory, and malaria sporozoite immunity: an hypothesis for immune evasion.

Prior to any exposure to malaria, most adults have T cells specific for malaria parasites and various malaria proteins. The protein for which this has been shown more than any other is the circumsporozoite protein (CSP) of Plasmodium falciparum. These T cells can be present in high frequency and appear to have arisen through exposure to other (non-malaria) organisms. Although T cells are thought to provide protection against sporozoites, these T cells specific for cross-reactive organisms are clearly unable to protect against malaria, and may be preferentially expanded following exposure to malaria sporozoites. Thus, cross-reactive organisms have the potential to skew the repertoire of sporozoite-induced T cells and affect the induction of protective immunity. This is analogous to the concept of 'original antigenic sin' whereby prior exposure to one strain of influenza virus was shown to be able to divert the antibody response to a second challenging strain to focus on the shared (cross-reactive) epitopes.