Comparative effect of bis-(beta-chloroethyl)-sulfide on basal and differentiated keratinocytes.

Bis-($\\beta$-Chloroethyl) sulfide (BCES), is a potent alkylating agent and a vesicant for human skin. The effect of BCES on basal and differentiated keratinocytes was studied using an epidermal culture and whole rat epidermis. A procedure was developed to expose the epidermal culture and the epidermis topically to various doses of BCES. It was verified autoradiographically that upon application of BCES to the surface of the culture, no spillage into the medium occurred. DNA was determined to be the primary target of BCES by studying the incorporation of $\\sp3$H-thymidine, $\\sp3$H-uridine and $\\sp{14}$C-leucine after epidermal cultures were exposed to doses of BCES ranging from 10 to 50 nmoles/cm$\\sp2$. Hence a parameter related to DNA damage was utilized in determining the sensitivity of the two epidermal cell populations to BCES. This parameter was the nucleoid sedimentation assay, which detects DNA single-str and breaks. The assay indicated that the basal cells are more susceptible to BCES than the differentiated cells. This higher susceptibility was determined to be a consequence of a higher level of alkylation of the basal cell DNA compared to the differentiated cell DNA following exposure to BCES. The level of DNA alkylation was measured using a CsCl density gradient to isolate the DNA. Comparable results were obtained using cells isolated from the epidermal culture and from the whole epidermis, thus supporting the use of the epidermal culture system for studying the cutaneous effects of a topically applied chemicals. Light microscopic observations of epidermal cultures exposed to BCES confirmed that the basal cells are more sensitive than differentiated cells, since basal cell destruction was observed after exposure to a dose of 10 nmoles/cm$\\sp2$ while the differentiated cells were affected only after exposure to the higher dose of 50 nmoles/cm$\\sp2$.Ph.D.Public healthPharmacologyUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/162357/1/9001705.pd