bromochloroacetic-acid and Vitiligo

In vitiligo, other than loss of melanocytes and melanin pigment in the lesional skin, keratinocytes are also involved. Human fetal Merkel cells are now generally considered to be derived from the epidermis. To date, no observations on Merkel cells in lesional skin of active vitiligo have been reported.. Merkel cells were identified by indirect immunofluorescence microscopy using the monoclonal antibody TROMA 1.. No TROMA 1-positive cells were observed in the vitiliginous skin lesions in any of the specimens examined, whereas normal numbers of these cells were seen in the adjacent pigmented skin.. This finding suggests that the processes that lead to damage of keratinocytes in vitiligo also involve other keratin-expressing cells such as the Merkel cells.

Topics: Adolescent; Adult; Antibodies, Monoclonal; Female; Fluorescent Antibody Technique; Humans; Keratinocytes; Keratins; Male; Middle Aged; Skin; Vitiligo

Cell cultures of human keratinocytes contain membrane-associated thioredoxin reductase that is extremely active in reducing radicals on the outer plasma membrane. This enzyme activity was confirmed by its purification from cultures of stratified human keratinocytes by affinity column chromatography. The enzyme was assayed both in vivo and in vitro using a spin-labeled quaternary ammonium compound as the substrate, under saturating conditions in free radical substrate. Specific activities were determined by monitoring the sequential decrease in the amplitude of the electron spin resonance signal per unit of cell protein. The following properties were found: Cultures of adult stratified cells have approximately twice the thioredoxin reductase activity of neonatal cells. The enzyme is inhibited by thioprotein inhibitors (i.e., parachloromecuribenzoate and dinitrochlorobenzene). The activity is regulated by calcium concentrations of the cell culture medium. Stratified keratinocytes are half as active in medium containing 2 mM Ca++ compared with 0.1 mM Ca++ concentration. Product inhibition of the enzyme occurs with oxidized coenzyme NADP+ (i.e., 87% inhibition of enzyme activity over 30 min). The enzyme is heat stable at temperatures of 70 degrees C for 10 min. It is inactivated at 75 degrees C. A comparative study of thioredoxin reductase activity on stratified differentiated and undifferentiated rapidly growing cells was performed. Also, enzyme activity was quantitated for cultured keratinocytes isolated from vitiliginous and normal skin of the same donor. The results of this study, and the connection between this enzyme activity and UV-generated free radicals are reconciled in terms of the mechanism of action and metabolic activity of thioredoxin reductase.

Topics: Adult; Biopsy; Free Radicals; Humans; Infant, Newborn; Keratins; NADH, NADPH Oxidoreductases; Reference Values; Skin; Spin Labels; Thioredoxin-Disulfide Reductase; Vitiligo

Light and electron-microscopic studies were performed on the amelanotic and adjacent normal-appearing skin in patients with vitiligo. The amelanotic skin revealed complete loss of pigment and absence of melanocytes. In addition to severe degenerative changes of melanocytes, varying degree of damage was also seen in the keratinocytes of normal-appearing skin adjacent to amelanotic skin.

Topics: Adult; Child; Female; Humans; Keratins; Male; Melanocytes; Skin; Vitiligo

Topics: Animals; Cell Division; Connective Tissue; Disease Models, Animal; Epithelial Cells; Humans; Keratins; Melanocytes; Pigmentation Disorders; Psoriasis; Skin; Skin Diseases; Skin Neoplasms; Vitiligo

Topics: Adhesiveness; Bandages; Basement Membrane; Biopsy; Diagnosis, Differential; Dihydroxyphenylalanine; Humans; Keratins; Langerhans Cells; Male; Melanocytes; Melanoma; Microscopy, Electron; Middle Aged; Pigmentation Disorders; Skin Neoplasms; Vitiligo

Topics: Dendrites; Germ Layers; Humans; Keratins; Microscopy, Electron; Pigmentation Disorders; Skin; Vitiligo