The role of UVB radiation in the induction and elicitation of photocontact hypersensitivity to TCSA in the mouse.

Overview

Photocontact hypersensitivity (PHS) to 3,3',4',5 tetrachlorosalicylanilide (TCSA) can be induced in mice by using cyclophosphamide as an immunopotentiator. Only UVA (320-400 nm) radiation was required for both sensitization and elicitation of PHS. The reaction was successfully transferred to syngeneic mice by injecting them with lymph node cells from sensitized donors, a finding that demonstrates the immunologic nature of PHS. The presence of UVB (280-320 nm) radiation was not necessary for sensitization and did not increase PHS beyond the levels observed with UVA radiation alone. Ultraviolet radiation in the UVB range (plus a small amount of UVA radiation) from FS40 sunlamps in the dose employed did not induce statistically significant PHS to TCSA, nor did it elicit a significant response in mice sensitized with TCSA plus UVA radiation. However, treatment of mice with UVB radiation at a distant site 6 days before sensitization suppressed the induction of PHS. This suppression appeared to be analogous to the systemic suppression of ordinary contact hypersensitivity in mice by UVB radiation.