Deoxyadenosine has been implicated as the toxic metabolite causing profound lymphopenia in immunodeficient children with a genetic deficiency of adenosine deaminase (ADA), and in adults treated with the potent ADA inhibitor deoxycoformycin. However, the biochemical basis for deoxyadenosine toxicity toward lymphocytes remains controversial. The present experiments have examined in detail the sequential metabolic changes induced in nondividing human peripheral blood lymphocytes by incubation with deoxyadenosine plus deoxycoformycin, or with 2-chlorodeoxyadenosine (CdA), an ADA resistant deoxyadenosine congener with anti-leukemic and immunosuppressive properties. The lymphotoxic effect of deoxyadenosine and CdA required their phosphorylation, and was inhibited by deoxycytidine. As early as 4 h after exposure to the deoxynucleosides, strand breaks in lymphocyte DNA began to accumulate, and RNA synthesis decreased. These changes were followed by a significant fall in intracellular NAD levels at 8 h, a drop in ATP pools at 24 h, and cell death by 48 h. Incubation of the lymphocytes with 5 mM nicotinamide, a NAD precursor and an inhibitor of poly(ADP-ribose) synthetase, prevented NAD depletion. The nicotinamide treatment also rendered the lymphocytes highly resistant to deoxyadenosine and CdA toxicity, without altering dATP formation or the accumulation of DNA strand breaks. The poly(ADPribose) synthetase inhibitor 3-aminobenzamide exerted a similar although less potent effect. These results suggest that NAD depletion, probably triggered by poly(ADP-ribose) formation, is the principle cause of death in normal resting human lymphocytes exposed to deoxyadenosine plus deoxycoformycin, or to CdA.

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''cell'' in circulation 3 in preoperative patients. Moreover, the To detect hepatocellular carcinoma (HCC) cells in the significant elevation of serum AFP protein levels sometimes circulating peripheral blood, we previously designed a lags behind the formation of a considerable recurrent mass. highly sensitive reverse-transcription polymerase chainBecause of the recent advances in the reverse-transcription reaction (RT-PCR) method targeting a-fetoprotein polymerase chain reaction (RT-PCR) technology, several (AFP) messenger RNA (mRNA). Using this method, we studies have been performed for detecting cancer cells in analyzed peripheral blood of in-and out-patients bearlymph nodes or peripheral blood in the form of specific ing HCC for 2 months consecutively and examined the mRNA, the existence of which means the presence of cells outcome thereafter. All 11 patients with recurrence eiproducing the mRNA. Such a system has been developed for ther in the liver alone or in both the liver and the lung melanoma cells, 4 breast cancer cells, 5 prostate cancer cells, 6 were positive for AFP mRNA. Among 10 recurrence-free and neuroblastoma cells. 7 Kar et al. 8,9 and Hillaire et al. 10 patients, 2 patients were AFP mRNA-negative and redetected the presence of albumin mRNA in peripheral blood mained recurrence-free during a period of 22 months of patients with HCC. But because a small amount of albumin observed. Four of 8 AFP mRNA-positive, recurrencemessage seems to be transcribed in nucleated blood cells, 3 free patients developed a clinically evident recurrence Matsumura et al. developed a RT-PCR system to detect AFP in the liver after 2 to 16 months. Seven of 8 preoperative mRNA in peripheral blood of HCC-bearing patients in 1994. 3 patients were already positive for AFP mRNA and the However, the serum AFP protein level in their HCC patients remaining negative patient became positive during surwas as high as 62,738 { 7,031 ng/mL, whereas the overall gery. Four of 6 preoperatively positive and still-alive papositive rate was 52%. For the practical usage in therapeutic tients had recurrence in the liver after 2 to 9 months.decision-making and early detection of recurrence, we conNone of the HCC-negative patients were positive for AFP structed an original, easy, and far more sensitive RT-PCR mRNA. We actually found an AFP protein-positive cell system for detecting AFP mRNA in circulation. 11 With this in peripheral blood obtained from one of the AFP method, only a single high-AFP-producing cell in 1 cc of whole mRNA-positive patients by immunostaining. The presblood was recognizable within 12 hours. 11 In the previous ent results suggest that circulating HCC cells may have study, using this system, we found five of seven HCC patients some relationship with the recurrence of HCC in the to be positive for AFP mRNA in their peripheral blood, liver. (HEPATOLOGY 1997;25:564-568.) whereas four patients with positive hepatitis virus marker(s) but negative for HCC and a healthy volunteer were negative. Hepatocellular carcinoma (HCC...

These results suggest that IL-2 and IL-8 are involved in the antigen-specific immune responses in most patients with FPIES. Further studies are needed to elucidate the significance of these cytokine in the pathogenesis of FPIES.