LETTERS TO THE inhibited this binding. In their paper Rubin et a/. (7) used calf thymus DNA radiolabeled by a modification of the Commerford method. We have observed that this way of labeling favors labeling of ss regions in the DNA. Circular PM2-DNA cannot be labeled this way. 3) It is obvious that in the absence of information about the inductive processes, one does not know whether DNA is merely a cross-reacting antigen. This is not only true for low-avidity anti-DNA, but also for high

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... y anti-DNA; the finding of high-avidity binding to ssDNA by low-avidity anti-dsDNA suggests that the affinity for DNA of both populations may not be so very different after all. As long as we are unaware of the processes that are responsible for induction of anti-DNA, the problem seems to be semantic to me.