Comparison of anti 60 and 52 kDa SS-A/Ro antibodies in the pathogenesis of cutaneous lupus erythematosus

Anti SS-A/Ro antibodies are involved in the pathogenesis of cutaneous lupus erythematosus (CLE) in a part through antibody dependent cellular cytotoxicity (ADCC). However, it is still obscure which and how anti 60 and anti 52 kDa Ro antibodies are involved. To address the issue, we examined both types of anti Ro antibodies of sera from patients with systemic LE (SLE) or discoid LE (LE). The titer of anti 60 kDa antibody in SLE was significantly much higher than that of DLE or control. The positive ratio of DLE showed more higher tendency than control, but it was not statistically significant. The similar tendency was observed in the titer of anti 52 kDa antibody. An association between the anti 60 kDa antibody and the anti 52 kDa antibody was statistically significant in SLE patients. Although the relative index (RI) was statistically significant in DLE, they included many negative sera, which biased the statistics. Both anti 60 kDa antibody and anti 52 kDa antibody could induce significant ADCC of ultraviolet B (UVB) light-irradiated keratinocytes from neonatal foreskins and/or normal adults, in which anti 60 kDa antibody showed higher cytotoxicity than anti 52 kDa antibody. The autologous combination studies (keratinocytes and monospecific anti 60 or anti 52 kDa antibody from patients) suggested anti 60 kDa antibody was more potent to induce ADCC activity than anti 52 kDa antibody. Taken together, it is likely that anti 60 kDa antibody dependent keratinocyte damage plays more significant role in the pathogenesis of SLE skin lesions than anti 52 kDa dependent damage. However, both type antibodies seemed to have little contribution to the pathogenesis of DLE skin lesion.