Are ACA and Scl 70 antibodies mutually exclusive?

Serological studies using indirect immunofluorescence, double immunodiffusion and immunoblot with recombinant Topo I and kinetochore antigens were performed in 180 patients with systemic scleroderma. In the sera of 10 patients, we found coexisting ACA and Scl 70 antibodies, and this was confirmed by all three methods. The relationship between the coexistence of these antibodies and the clinical features of the disease is not clear, although in all these cases there was pronounced vascular involvement.