Reactivity and Persistence of Local Immunological Memory on Murine Contact Hypersensitivity

In a rechallenge system examining murine contact hypersensitivity to DNFB in BALB/c mice, the reactivity to the specific antigen at the previously responded site and the persistence of an immunological memory were investigated. Flare-up reactions were induced 4 weeks after the first challenge only at the previously responded site by local or systemic administrations of minute quantities of a specific antigen. The intensity of ear swelling was dependent on the quantity of applied antigen at the time of the rechallenge. The local hypersensitivity to the specific antigen observed in the previously responded site and the regional lymph node persisted for at least 1 year. These results suggest that the sensitivity to a specific antigen at the previously responded site is intensified and the immunological memory persists for a long time. This may explain the mechanisms by which chronic contact dermatitis recurs readily at the limited site by exposure to minute quantities of causative antigens.     

Endogenous oxalogenesis after acute intravenous loading with ethylene glycol or glycine in rats receiving standard and vitamin B6‐deficient diets

Objectives: The effect on endogenous oxalate synthesis of acute intravenous loading with ethylene glycol or glycine was investigated in rats on a standard or a vitamin B6‐deficient diet. Methods: Twenty‐four male Wistar rats weighing approximately 180 g were randomly divided into ethylene glycol and glycine groups of 12 animals each. These groups were further divided into two subgroups of six animals each that were fed either a standard or a vitamin B6‐deficient diet for 3 weeks. Animals of these two subgroups received an intravenous infusion of 20 mg (322.22 µmol) of ethylene glycol or 100 mg (1332.09 µmol) of glycine, respectively. Urine samples were collected just before intravenous infusion of each substance and at hourly intervals until 5 h after receiving the infusion. Urinary oxalate, glycolate, and citrate levels were measured by capillary electrophoresis. Results: Urinary oxalate and glycolate excretion was significantly increased after ethylene glycol administration. Significant differences between the control and vitamin B6‐deficient groups were found. In contrast, there were only small changes of oxalate and glycolate excretion after glycine administration. Recovery of the given dose of ethylene glycol as oxalate in 5‐h urine was 0.31% and 7.15% in the control and vitamin B6‐deficient groups, respectively, whereas recovery of glycolate was 0.68% and 7.22%, respectively. Conclusions: Ethylene glycol loading has a significant effect on urinary oxalate excretion in both normal and vitamin B6‐deficient rats, whereas glycine loading only has a small effect. Oxalate and glycolate excretion after ethylene glycol loading were respectively 23‐fold and 11‐fold higher in vitamin B6‐deficient rats than in controls.     

Experimental chloroquine myopathy: morphological and biochemical studies

Morphological and biochemical studies were performed on the soleus muscles of rats receiving a daily intraperitoneal injection of 50 mg chloroquine chloride (CQ) per kilogram of body weight. Light microscopy showed mild to moderate variations in fiber size, numerous dense membranous bodies and vacuoles. The vacuoles were ringed by material that was intensely basophilic in hematoxylin-eosin preparations, resembling rimmed vacuoles in the muscle fibers of distal myopathy. Segmental degradation or necrosis was often observed. The 3H-leucine uptake by myofibrillar and soluble sarcoplasmic fractions in CQ-treated muscles was the same as in the controls. The significant increases in lysosomal (cathepsin B & L, B and D) proteases and thiol protease inhibitor occurred in the earlier stages of CQ-induced myopathy, when hardly any autophagic vacuoles or dense bodies were observable by light microscopy. We conclude that the over-development of autophagic vacuoles and the significant increases in lysosomal protease activity in muscle tissues may be important in the development of the focal degradation and necrosis of CQ-treated muscles.     

Establishment of a peripheral T-cell lymphoma cell line showing amplification of the c-myc oncogene

A new T-cell lymphoma cell line, designated T34, was established from freshly isolated lymph node tumor cells of a patient with non-Hodgkin's diffuse large cell lymphoma. The T34 cells, as well as the parental lymphoma cells, showed mature helper/inducer immunophenotypes in that they formed spontaneous sheep erythrocyte rosettes and reacted with OKT-3 and OKT-4 monoclonal antibodies. They were negative for OKT-6, OKT-8, terminal deoxynucleotidyl transferase, WT-1, and HLA-DR antigens. Molecular analysis revealed that the T34 cells contained 8- to 16-fold amplified c-myc DNA. The same genetic change was observed in parental lymphoma cells, indicating that the c-myc amplification had occurred in vivo. There was no gross rearrangement of the c-myc DNA. The c-myc gene of the T34 cell line was actively transcribed into normal-sized c-myc mRNA. Cytogenetic analysis showed that both the T34 and the parental lymphoma cells had a near-triploid karyotype with multiple structural chromosome changes. The terminal end of the long arm of chromosome No. 8, the chromosomal locus of single-copy c-myc, was elongated (8q+ chromosome), perhaps reflecting the site of c-myc amplification. These data suggested that amplification of the c-myc oncogene played some role in progression and proliferation of this peripheral T-cell neoplasm.     

Effects of various inducers on the activities of cytochrome P-450-mixed function oxidases and aflatoxin B1 activation in microsomes of hamster livers

The effects of various inducers on the activities of drug-metabolizing enzymes including aflatoxin B1 activation were studied in Syrian golden hamsters. Activity for aflatoxin B1 was determined by aflatoxin B1-DNA adducts formation. The treatments of hamsters with 3-methylcholanthrene, alpha-naphthoflavone and benzo(a)pyrene elevated markedly the activity for aflatoxin B1 by 2460, 1380 and 450%, respectively. Phenobarbital induced slightly and isosafrole and ethanol did not induce the activity for aflatoxin B1. Pregnenolone-16 alpha-carbonitrile decreased aflatoxin B1 activation to 51% of that of the non-treated animals. These results were in good accordance with the induction rate of a form of cytochrome P-450 (P-450AFB) which has potent activity to aflatoxin B1. Characteristics in the induction of mixed function oxidases of hamsters by these inducers, especially in respect to benzo(a) pyrene metabolizing enzyme, seemed to differ from those of rats. These results suggest that the activity for aflatoxin B1 in hamster is inducible by 3-methylcholanthrene-type inducers and that hamster is a suitable animals model to study the mechanism of aflatoxin B1-hepatocarcinogenesis.