Possible role of Hsp70 in autoantigen shuttling to the dermo-epidermal junction in systemic lupus erythematosus.

The lupus band is the result of immune complex deposition along the dermo-epidermal junction; such complexes are formed in situ by the interaction of antinuclear antibodies with their respective autoantigens. Dermal autoantigens are released after sun exposure, concurrently a heat shock protein production take place and would participate in autoantigen transfer to the dermo-epidermal junction. In this work the presence of Hsp70 along with the lupus band was investigated by immunofluorescence in twenty SLE skin biopsies. Immune deposits were mainly composed by IgM, IgG and C3 and were found in all lupus biopsies at the dermo-epidermal junction. Immunoreagents were also present into papillary vessels and, with less extent, into epidermal keratinocytes. Hsp70 was present in 60% of lupus biopsies, and was mainly distributed along dermo-epidermal junction and around papillary vessels. Furthermore, by double fluorescence labelling assays, we found that immuno-reactants are co-localized with Hsp70. Our results suggest that Hsp70 would shuttle autoantigens to the dermo-epidermal junction.