High Altitude Impairs In Vivo Immunity in Humans

Abstract

The aim was to assess the effect of high altitude on the development of new immune memory (induction) using a contact sensitization model of in vivo immunity. We hypothesized that high-altitude exposure would impair induction of the in vivo immune response to a novel antigen, diphenylcyclopropenone (DPCP). DPCP was applied (sensitization) to the lower back of 27 rested controls at sea level and to ten rested mountaineers 28 hours after passive ascent to 3777 m. After sensitization, mountaineers avoided strenuous exercise for a further 24 hours, after which they completed alpine activities for 11-18 days. Exactly 4 weeks after sensitization, the strength of immune memory induction was quantified in rested mountaineers and controls at sea level, by measuring the response to a low, dose-series DPCP challenge, read at 48 hours as skin measures of edema (skinfold thickness) and redness (erythema). Compared with control responses, skinfold thickness and erythema were reduced in the mountaineers (skinfold thickness,-52%, p=0.01, d=0.86; erythema, -36%, p=0.02, d=0.77). These changes in skinfold thickness and erythema were related to arterial oxygen saturation (r=0.7, p=0.04), but not cortisol (r<0.1, p>0.79), at sensitization. In conclusion, this is the first study to show, using a contact sensitization model of in vivo immunity, that high altitude exposure impairs the development of new immunity in humans.

Exercise Intensity and Duration Effects on In Vivo Immunity

“…Intradermal injections of high-dose corticosterone or catecholamines, both locally or distant from the sensitization site, inhibit the antigenpresenting capability of cutaneous DCs, reduce the number of T cells in draining lymph nodes, and ultimately suppress DTH and CHS responses (11,15,33). Results from human studies are less consistent, with some authors reporting a lack of association between stress hormones and in vivo immune responses (3,13,28). One frequently proposed explanation is that human studies typically rely on individual snapshot assessments of circulating stress hormones, thus missing important information regarding the kinetics of these responses.…”

Exercise, immune function and respiratory infection: An update on the influence of training and environmental stress

“…Although there is continued debate over the benefits to sport performance, 57,58 there is relatively little discussion and research about how various altitude-training methods affect immunity and host defence in athletes. This is concerning as the current consensus is that altitude and hypoxic exposure decrease both in vivo and in vitro cell-mediated immune function and increase self-reported respiratory infection ( Table 2) 38,[59][60][61][62][63][64][65][66] : this remains the case even when considering only studies involving high-level athletes (Table 3). 59,60,64 Nevertheless, caution is required when interpreting findings from studies of selfreported URTI at altitude as there is considerable overlap between symptoms of upper airway infection and acute mountain sickness.…”

The Circulatory and Metabolic Responses to Hypoxia in Humans – With Special Reference to Adipose Tissue Physiology and Obesity

“…Second, hypoxia is associated with impaired cognitive performance, which may persist even after the cessation of hypoxic exposure (64). Third, hypoxic exposure is known to impair human immune system function (65), which may be detrimental in fighting against pathogens and other triggers of communicable diseases. Fourth, hypoxia is capable of inducing fibrosis in cardiac muscle (66), which increases the stiffness of the heart.…”