RESUMO
Despite their hematopoietic origin, mast cells (MCs) develop exclusively in tissues, hampering their ample use in research. To circumvent this problem, tissue-derived MCs are typically first expanded in culture, but the changes MCs may undergo in the novel micromilieu are poorly defined. Here, we monitor skin MCs from a number of donors over time, revealing profound yet non-synchronized modulations in culture. While tryptase and chymase, the most specific markers, strongly decline, FcεRI surface expression, and FcεRI-mediated histamine release steeply increase (from ≈15.5% to ≈60%), replicated by similar increments in TNF-α secretion. Interestingly, the modulations are independent of cell cycle progression, as they are comparable in the growth and postgrowth phase, implying they primarily result from microenvironmental conditioning. The data highlight a high degree of MC versatility, but also advise that results based on cultured MCs should be viewed with some caution, as they may not accurately reflect their counterparts in situ.
Assuntos
Mastócitos/citologia , Pele/citologia , Técnicas de Cultura de Células , Ciclo Celular , Linhagem da Célula , Células Cultivadas , Quimases/genética , Quimases/metabolismo , Liberação de Histamina , Humanos , Mastócitos/imunologia , Mastócitos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de IgE/genética , Receptores de IgE/metabolismo , Pele/imunologia , Pele/metabolismo , Triptases/genética , Triptases/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Human skin mast cells proliferated in the presence of interleukin (IL)-4+SCF (expanding 18-fold in 8 weeks) and acquired profound responsiveness towards high affinity IgE receptor (FcεRI) cross-linking, liberating about 75% of their histamine. In a proof-of-concept, we found that these cells are useful for pharmacological testing. Even a subtle inhibition of degranulation can be visualized. This model might prove valuable in tests of novel anti-allergic drugs.
Assuntos
Antialérgicos/farmacologia , Avaliação Pré-Clínica de Medicamentos/métodos , Mastócitos/citologia , Receptores de IgE/química , Pele/citologia , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Humanos , Interleucina-4/farmacologia , Mastócitos/efeitos dos fármacos , Mastócitos/metabolismo , Receptores de IgE/metabolismo , Fator de Células-Tronco/farmacologia , Fatores de TempoRESUMO
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 alpha (FcepsilonRIalpha) and FcepsilonRIgamma but less FcepsilonRIbeta than sMC and displayed slightly reduced, but robust FcepsilonRI-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.
