Quantitative and 3-dimensional analysis of Langerhans' cells following occlusion with patch tests using confocal laser scanning microscopy.

Quantitative and detailed 3-dimensional (3-D) morphological information can be obtained from the same tissue volume using a confocal laser scanning microscope (CLSM). In the present study, we used CLSM for evaluation of Langerhans' cells (LC) in human skin at 0 h, 24 h and 48 h following occlusion with patch tests for 48 h. The relative volume of epidermal CD1a reactivity was quantified with CLSM on 25 microns thick sections stained with indirect immunofluorescence. No statistically significant difference was found when comparing the values obtained on the biopsy specimens from occluded skin (n = 36) with those from non-occluded skin (n = 9). Nor were any statistically significant changes detected in the number of epidermal CD1a+ cells as determined with immunoperoxidase staining between occluded and non-occluded skin. The occlusion produced a transient mild inflammatory reaction with an induced expression of intercellular adhesion molecule-1 (ICAM-1) on keratinocytes and an increased number of CD3+ epidermal lymphocytes. In addition, 3-D reconstructions revealed spatial information on the distribution of LC dendrites towards the skin surface.