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Mast cells ( MCs) are unique constituents of the human body. While inter-individual differences may influence the ways by which MCs operate in their skin habitat, they have not been surveyed in a comprehensive manner so far. We therefore set out to quantify skin MC variability in a large cohort of subjects. Pathophysiologically relevant key features were quantified and correlated: transcripts of c-kit, Fc ε RI α, Fc ε RI β, Fc ε RI γ, histidine decarboxylase, tryptase, and chymase; surface expression of c-Kit, Fc ε RI α; activity of tryptase, and chymase; histamine content and release triggered by Fc ε RI and Ca2+ ionophore. While there was substantial variability among subjects, it strongly depended on the feature under study (coefficient of variation 33-386%). Surface expression of Fc ε RI was positively associated with Fc ε RI α mRNA content, histamine content with HDC mRNA, and chymase activity with chymase mRNA. Also, MC signature genes were co-regulated in distinct patterns. Intriguingly, histamine levels were positively linked to tryptase and chymase activity, whereas tryptase and chymase activity appeared to be uncorrelated. Fc ε RI triggered histamine release was highly variable and was unrelated to Fc ε RI expression but unexpectedly tightly correlated with histamine release elicited by Ca2+ ionophore. This most comprehensive and systematic work of its kind provides not only detailed insights into inter-individual variability in MCs, but also uncovers unexpected patterns of co-regulation among signature attributes of the lineage. Differences in MCs among humans may well underlie clinical responses in settings of allergic reactions and complex skin disorders alike. [ABSTRACT FROM AUTHOR]

The article offers information on the characteristics of mast cells in skin tissues and discusses the variability in them in different cohorts through an analysis. Topics discussed include the morphology of the cells, the granules in mast cells, and the differences in mast cells based on the location of the skin on the body.

The coincidence of skin tumors and elevated mast cell (MC) numbers has been known for many years. However, it has remained controversial whether, in this context, MCs promote or inhibit tumor growth. Addressing this problem, different melanoma and squamous cell carcinoma cell lines were co-cultivated with primary, dermal MC for 24 h and gene or protein expression of cytokines tumor necrosis factor (TNF-α), interleukin-6 (IL-6) and interleukin-8 (IL-8) estimated. Co-culture with MCs led to an increase in IL-8 gene expression and IL-8 protein release from melanoma cells and IL-6 and IL-8 gene expression and protein release from squamous cell carcinoma cells, respectively. Moreover induction of IL-6 and IL-8 was primarily regulated by MC-derived TNF-α. Our data suggest an interplay between MCs and tumor cells, which results in altered cytokine release and may, thus, have an impact on tumor growth, invasion and neovascularisation. [ABSTRACT FROM AUTHOR]

Please cite this paper as: Mast cell lines HMC-1 and LAD2 in comparison with mature human skin mast cells – drastically reduced levels of tryptase and chymase in mast cell lines. Experimental Dermatology 2010; 19: 845–847. To circumvent the costly isolation procedure associated with tissue mast cells (MC), two human MC lines, i.e. HMC-1 and LAD2, are frequently employed, but their relation to mature MC is unknown. Here, we quantitatively assessed their expression of MC markers in direct comparison to skin MC (sMC). sMC expressed all lineage markers at highest and HMC-1 cells at lowest levels. LAD2 cells expressed comparable high-affinity IgE receptor α (FcεRIα) and FcεRIγ but less FcεRIβ than sMC and displayed slightly reduced, but robust FcεRI-mediated histamine release. Only minor differences were found for total histamine content and c-Kit expression. Huge, and to this level unexpected, differences were found for MC tryptase and chymase, with sMC >>> LAD2 > HMC-1. Taken together, HMC-1 cells represent very immature malignantly transformed MC, whereas LAD2 cells can be considered intermediately differentiated. Because of the minute levels of MC proteases, MC lines can serve as surrogates of tissue MC to a limited degree only. [ABSTRACT FROM AUTHOR]