Peripheral blood serum from healthy donors contains antibodies against the fragment of transcribed region of ribosomal repeat.

Enzyme immunoassay showed that blood serum from healthy donors contains specific high-affinity antibodies (apparent association constant > or = 5 x 10(9) M(-1)) against a fragment of transcribed region of ribosomal DNA repeat of human serum, which are present in a free form or are bound to extracellular DNA. Preheating of the serum at 55 degrees C and high ionic strength (1.5 M NaCl) had no effect on the interaction of antibodies with this fragment.

Stimulatory effect of fragments from transcribed region of ribosomal repeat on human peripheral blood lymphocytes.

Fragments from the transcribed region of the ribosomal repeat include considerable amounts of unmethylated CpG DNA motifs. These motifs activate immune cells via the interaction with Toll receptors. In vitro experiments confirmed the stimulatory effect of transcribed region of ribosomal repeat on human lymphocytes.