Influence of sodium lauryl sulphate on 2,4-dinitrochlorobenzene-induced lymph node activation.

The influence of the anionic surfactant sodium lauryl sulphate (SLS) on the ability of the contact allergen 2,4-dinitrochlorobenzene (DNCB) to provoke draining lymph node cell proliferative responses, a correlate of skin sensitizing potential, has been examined in mice. Topical application of 10% SLS with 0.1% DNCB caused a more vigorous proliferative response than did exposure to 0.1% DNCB alone. Lower concentrations (0.1% or 1%) of SLS were ineffective and 10% SLS failed to influence proliferative responses to higher concentrations (0.5% or 1%) of DNCB. Using an in vitro model for measurement of percutaneous absorption 10% SLS was shown not to increase the skin penetration of 0.1% DNCB. We therefore examined the influence of SLS on the accumulation of dendritic cells (DC) in lymph nodes draining the site of exposure, an important early event during the induction phase of skin sensitization. The frequency of DC in draining nodes was measured following topical application of SLS, DNCB or a combination of both. Epicutaneous exposure to 0.1% DNCB caused only a modest increase in the number of lymph node DC. However, 10% SLS or a mixture of 10% SLS with 0.1% DNCB each resulted in a significant elevation of DC numbers. It is proposed that SLS augments the skin sensitizing potential of sub-irritant concentrations of DNCB via an increase in the number of immunostimulatory DC which reach the draining nodes.