VLA protein expression on epidermal cells (keratinocytes, Langerhans cells, melanocytes): a light and electron microscopic immunohistochemical study

Abstract

The very late antigens, or VLA proteins, are a family of cell surface heterodimers (alpha 1-b beta 1) that mediate cell adhesion to specific components of the extracellular matrix (collagens, fibronectin, laminin). In normal human epidermis, the common VLA beta 1 subunit is expressed on basal keratinocytes (BK). Langerhans cells (LC) and melanocytes. By means of light and electron microscopic immunostaining procedures, we have investigated the distribution of VLA alpha 1,2,3,4,6 subunits on normal human adult and foetal epidermal cells. alpha 1 antigen expression was not observed on any epidermal cell type. Both during foetal development and in adult epidermis, alpha 2 and alpha 3 were strongly expressed on the cell membrane BK, while alpha 6 was mainly expressed at their dermal pole. These different patterns of distribution suggest that the alpha 6 subunit may mediate BK anchorage to the basement membrane zone, while the alpha 2 and alpha 3 subunits may also be involved in intracellular adhesion. Moreover, with immunoelectron microscopy, LC were seen to be weakly alpha 5 and alpha 6 positive and melanocytes were alpha 3 and alpha 6 positive. Thus, VLA proteins are expressed by epidermal cells in a cell-type-specific pattern that could be related to particular functional roles of these proteins.

Kinetics and regulation of human keratinocyte stem cell growth in short-term primary ex vivo culture. Cooperative growth factors from psoriatic lesional T lymphocytes stimulate proliferation among psoriatic uninvolved, but not normal, stem keratinocytes.

“…Epidermal cell cultures in KBM + 1% FBS media consist mainly (> 95%) of keratinocytes; however, it is possible that melanocytes and Langerhans cells may proliferate in cultures stimulated by T cells. Like the keratinocyte stem cell-containing population, melanocytes and Langerhans cells are also /1 integrin+ Ki/K1O-in in vivo epidermis (4,43,44). Therefore it was important to determine whether melanocytes or Langerhans cells are present in the /1 integrinbnight Ki /K1 0-population in the short-term cultures and to quantitate their contribution to the enhanced proliferation of the /31 integrinbMght KI/K1O-population after exposure to lesional psoriatic T cell supernatant.…”

“…This was accomplished by costaining short-term cultured psoriatic uninvolved epidermal cells with anti-/I3 integrin plus anti-vimentin monoclonal antibodies. (Anti-vimentin stains Langerhans cells, melanocytes, and infiltrating lymphoid cells in the epidermis [44]. )…”

Beta-1 Integrins in the Normal Human Glomerular Capillary Wall: An Immunoelectron Microscopy Study

“…A strong staining of basal kératinocytes with anti-a2, a 3 and ra* MoAb, and an ra5 labelling of dermal fibroblasts were regularly detected, as previously described [23]. Negative controls consisted of: (a) replacement of the primary MoAb with mouse IgG of matched isotype (Chemicon International Inc., El Segundo, Calif., USA) or normal rat serum (Chemicon); (b) replacement of the MoAb with the respective buffer solution.…”

Adhesion Molecules in Atopic Dermatitis: Upregulation of α6 Integrin Expression in Spontaneous Lesional Skin as well as in Atopen, Antigen and Irritative Induced Patch Test Reactions

“…Staining by EAl mAb was low and found on the entire endothelial cell surface. Furthermore, the basal surface o f basal kératino cytes, adjacent to the basement membrane zone, expressed ab integrin similar to the thymic epithelium [20] and as described by other authors [9,30]. In the epidermis the a6 integrin associates primarily and probably exclusively with the (34 integrin subunit [31][32][33][34] the lamina lucida of human epidermal basal membrane (la minin 5 and 1).…”