The basal keratinocytes
constitute the floor of the blister and do not lose their attachment to the basement membrane zone.
Basal cell vacuolar degeneration and necrotic basal keratinocytes
are seen in both LE and EM because of dysregulated apoptosis preceded by immunologic response initiated by unidentifid HSV, EBV or other viral infections crossreacting with lupus autoantigens.
There is increasing evidence that HPV is not cleared when lesions regress but as in COPV (45), CRPV (46) and BPV (47) infection remains in a latent state in a few basal keratinocytes
Moderate expression of TNF[alpha] was found in inflammation cells, the basal keratinocytes
, and blister fluid (Figure 2).
The persistent expression of IL-17A in basal keratinocytes
seems to induce target cell to secrete significant amounts of IL-6, resulting in high levels of circulating IL-6 and sIL-6/IL-6R heterodimers ; increased levels of local and systemic IL-6 influence IL-6R-alpha+ neutrophils and monocytes activity, leading to aberrant chemotaxis into lesional skin and formation of intraepidermal neutrophil microabscesses .
Cytokeratin 14 stains normal basal keratinocytes
of the epidermis (10,34) as well as follicular outer root sheath epithelium.
IL-1[alpha] induces growth factors in fibroblasts that can bind to receptors on the basal keratinocytes
to promote proliferation .
Today, there is a growing body of evidence that LP represents a T cell-mediated autoimmune damage to basal keratinocytes
that express altered self- antigens on their surface.23 However, in regard to the periodic colocalization of lichen planus and vitiligo, diverse theories have been proposed; for example, one theory argues that suppressor T cells of LP become uninhibited by the change in antigen expression caused by vitiligo.
Physiological and retinoid-induced proliferations of epidermis basal keratinocytes
are differently controlled.
PV and PF can appear identical on direct immunofluorescence, even though the blister cleavage plane is very high in PF and usually just above the basal keratinocytes
This histological feature is distinct from the melanocytes of freckles where normal number of melanocytes which are more pigmented due to increased melanin in basal keratinocytes
(fig-1).1 While freckles are found almost exclusively on sun-exposed areas of the body, lentigenes may occur on all parts of the body and typically do not darken with sun exposure (as compared to freckles).
Mild reactive squamous atypia, particularly of basal keratinocytes
, is quite common.