Figure 4

Double immunoreactivity for Cdsn (10-nm gold) and involucrin (5-nm gold) in normal (a) and psoriatic skin (b and c). a, In normal skin, desmosomes (D) on cells at the interface between the stratum granulosum and stratum corneum demonstrate colocalization of Cdsn (arrows) (10-nm gold) and involucrin (arrowheads) (5-nm gold). Cell membranes show involucrin labeling (arrowheads) consistent with initiation of cell envelope assembly. b, In psoriatic epidermis, keratinocytes within the stratum spinosum where Cdsn (arrows) is beginning to be incorporated into desmosomes also show labeling of cell membranes for involucrin (arrowheads). Neither Cdsn nor involucrin labeling is seen in equivalent cell layers in normal skin. These findings in psoriatic epidermis are consistent with earlier release of Cdsn and earlier cell envelope formation than seen in normal skin. c, In mature cornified cell envelopes from the superficial epidermis of psoriatic skin, desmosomes (D) show increased labeling for Cdsn (arrow) compared with those desmosomes at lower levels in the epidermis (shown in b). This suggests that extracellular Cdsn release is complete (arrow) although cell envelope-associated involucrin immunolabeling (arrowheads) implies that the cell envelope is not fully mature. Scale bar: 0.1 μm.