An oligonucleotide with a nucleotide sequence of 5'-cctcctcctcctcctcctcctcct-3' inhibits proliferation of human PBMC activated by TLR9 agonist and interferon production from human PBMC induced by TLR9 agonist, HSV-1, flu virus and serum from SLE patients, and rescues the mice from cytokine-mediated lethal shock. This oligonucleotide can be used as a- remedy for the treatment of systemic lupus erythematosus (SLE), sepsis, multiple organ dysfunction syndromes and other immune-mediated disorders.