A suction blister model reliably assesses skin barrier restoration and immune response

Skin wound healing models can be used to detect changes in immune function in response to interventions. This study used a test-retest format to assess the reliability of a skin suction blister procedure for quantitatively evaluating human immune function in repeated measures type studies. Up to eight suction blisters (~30 mm(2)) were induced via suction on each participant's left and right forearm (randomized order; blister session 1 and 2), separated by approximately one week. Fluid was sampled from each blister, and the top layer of each blister was removed to reveal up to eight skin wounds. Fluid from each wound was collected 4, 7 and 24h after blisters were induced, and proinflammatory cytokines were measured. Transepidermal water loss (TEWL), to assess skin barrier recovery, was measured daily at each wound site until values were within 90% of baseline values (i.e., unbroken skin). Sleep, stress and inflammation (i.e., factors that affect wound healing and immune function), preceding the blister induction, were assessed via activity monitors (Actical, Philips Respironics, Murrysville, Pennsylvania), the Perceived Stress Scale (PSS) and C-reactive protein (CRP), respectively. Area-under-the-curve and TEWL, between blister session 1 and 2, were compared using Pearson correlations and partial correlations (controlling for average nightly sleep, PSS scores and CRP). The suction blister method was considered reliable for assessing immune response and skin barrier recovery if correlation coefficients reached 0.7. Volunteers (n=16; 12 M; 4F) were 23 ± 5 years [mean ± SD]. Time to skin barrier restoration was 4.9 ± 0.8 and 4.8 ± 0.9 days for sessions 1 and 2, respectively. Correlation coefficients for skin barrier restoration, IL-6, IL-8 and MIP-1α were 0.9 (P<0.0001), 0.7 (P=0.008) and 0.9 (P<0.0001), respectively. When average nightly sleep, PSS scores and CRP (i.e., percent difference between sessions 1 and 2) were taken into consideration, correlations in immune response between sessions 1 and 2 were improved for IL-8 (0.8, P=0.002) and TNF-α (0.7, P=0.02). The skin suction blister method is sufficiently reliable for assessing skin barrier restoration and immune responsiveness. This data can be used to determine sample sizes for cross-sectional or repeated-measures types of studies testing the impact of various stressors on immune response, and/or the efficacy of interventions to mitigate decrements in immune response to stress.