T-lymphocytes from AIDS patients are unable to synthesize ribonucleotides de novo in response to mitogenic stimulation. Impaired pyrimidine responses are already evident at early stages of HIV-1 infection. - Bofill,M.; Fairbanks,L.D.; Ruckemann,K.; Lipman,M.; Simmonds,H.A. (J Biol Chem, 1995)