Mixed connective tissue disease (MCTD)--its immunological characteristics.

The concept of the MCDT is controversial; it is still not settled whether it is nosological entity, or a variety of SLE, or a special variety of scleroderma. From the practical point of view the authors consider it important to perform tests for RNA antibodies whenever the characteristics of different collagenoses coexist. Detection of the antibodies is relevant both to the prognosis and the choice of treatment.