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Comparative study of Langerhans cells in normal and pathological human scars. II. Hypertrophic scars
C Cracco1, M Stella, S Teich Alasia
1Dipartimento di Anatomia e Fisiologia Umana, Università di Torino, Italy.
Insights
Langerhans cells (LCs) in hypertrophic scars show distinct changes, suggesting an immune basis for these skin conditions. Two scar types reveal altered LC density, morphology, and HLA-DR expression, indicating immune activation.
Area of Science:
- Immunodermatology
- Wound Healing Research
- Cellular Biology
Background:
- Langerhans cells (LCs) are key immune cells in skin, with altered characteristics observed in various skin diseases.
- Hypertrophic scars are increasingly recognized to have an immunological component.
Purpose of the Study:
- To investigate the role and characteristics of Langerhans cells (LCs) in human hypertrophic scars.
- To explore the potential immunological basis of hypertrophic scarring through LC analysis.
Main Methods:
- Histological examination of hypertrophic scar biopsies using hematoxylin and eosin staining.
- Immunofluorescence and immunoperoxidase techniques to identify CD1a-positive LCs.
- Analysis of LC density, distribution, morphology, and HLA-DR expression on keratinocytes.
Main Results:
- Two distinct types of hypertrophic scars were identified based on LC characteristics.
- Type 1 scars showed increased LC density, larger cell size, and prominent dendritic networks in epidermis and dermis, with anomalous HLA-DR expression.
- Type 2 scars had normal epidermal LC density but increased dermal LCs, with less pronounced dendritic projections and weaker HLA-DR expression.
Conclusions:
- The findings suggest an immunologically activated state in hypertrophic scars.
- Morphological data on LCs support the involvement of the immune system in hypertrophic scar formation.
- Distinct LC patterns may differentiate subtypes of hypertrophic scarring.
Abstract:
Langerhans cells (LCs) seem to play a crucial role in the immune system of the skin. Changes in their density, distribution, phenotype and/or morphology have been described in a number of skin diseases, mostly immunologically mediated. For this reason, we investigated LCs in human hypertrophic scars, since these scars are presently believed to have an immunological basis. A preliminary analysis of the histological features was carried out on vertical serial sections, stained with hematoxylin and eosin. Both epidermal and dermal components of hypertrophic scar biopsies were examined. The total epidermal thickness and the thickness of the single epidermal layers were also measured; the values obtained were similar to those of control skin and normotrophic scars. Subsequently, CDla-positive LCs, revealed by indirect immunofluorescence and immunoperoxidase techniques, were studied to determine their position among the epidermal layers and within the dermis, their dimensions, their density and their morphology. According to these observations, two main types of hypertrophic scars were identified. In the first type (7 scars), LCs were widely clustered within both the whole epidermis and the dermis. Their density was increased (about 750 cells/mm2 of epidermal area), if compared to control skin and normotrophic scars (both about 400 cells/mm2 of epidermal area; p less than 0.001). The epidermal cell profiles, nearly three times larger than those of control skin, exhibited a dense network of interconnected dendrites. Further analysis for the presence of HLA-DR molecules revealed an anomalous expression of these antigens on keratinocytes. In the second type (3 scars), LCs density within the stratum Malpighii was unchanged, relative to control skin and normal scars, while CDla-positive cell bodies remained numerous in basal position and within the subpapillary corion. Epidermal LCs, only slightly larger than those evidentiated in control skin, displayed short and retracted dendritic projections. The aberrant expression of HLA-DR antigens on keratinocytes was very weak and sparse. The present results strongly suggest an immunologically activated state of the tissues examined; they provide morphological data that support the involvement of the immune system in hypertrophic scarring.