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Circadian rhythmicity of delayed hypersensitivity to oxazolone in the rat.

1. A marked circadian rhythm was detected in the ear swelling of rats immunized and then challenged with oxazolone. 2. The peak response observed at 10.00 hours was over eight times the minimum at 16.00 hours. 3. As related tests are used frequently in man greater attention to clock time is necessary in clinical immunology.

Animals↗

The prognostic significance of delayed hypersensitivity to dinitrochlorobenzene and mechlorethamine hydrochloride in cutaneous T cell lymphoma.

Recent studies suggest that cells elaborating type 1 cytokines are important mediators of anti-tumor cell-mediated immunity in cutaneous T cell lymphoma. Type 1 cell-mediated immune responsiveness was assessed in 276 patients with cutaneous T cell lymphoma (mycosis fungoides and Sézary syndrome) using 2,4-dinitrochlorobenzene (DNCB) skin testing as part of the initial evaluation. The overall rate of sensitization after one and two DNCB challenges was 32% and 67%, respectively, which is much decreased compared with the expected rate of more than 95% for normal individuals. Moreover, the frequency of DNCB sensitization and allergic contact dermatitis to topically applied mechlorethamine decreased with advancing stage of disease. In addition to the expected strong correlation with stage, we observed that patients who were DNCB test positive were significantly less likely to experience disease progression and had a better overall prognosis compared with DNCB-negative patients. These results support the concept that cell-mediated responses are important in cutaneous T cell lymphoma, and that augmentation of these responses would be therapeutically beneficial.

Administration, Topical↗

A study on delayed hypersensitivity to rotavirus in infancy and childhood.

The T-cell responsiveness to rotavirus antigen and phytohaemagglutinin (PHA) together with T-cell total and subsets quantitation was carried out in 50 non-diarrhoeal and six rotavirus diarrhoeal subjects. All individuals in the non-diarrhoeal group responded well to PHA and had normal values for T-cell subsets. The number of positive responders to the rotavirus antigen increased gradually from 0% in the newborns to 92% in older children. The increasing risk of exposure to rotavirus infection is thought to be a chief cause of this age-related variation. All the rotavirus diarrhoeal patients responded well to the rotavirus antigen, indicating a potent test system. The T-cell responses to PHA and the T-cell subsets were significantly low. This could be due to temporary T-cell suppression that may accompany viral infection. Our results are discussed in the context of previous studies.

Antigens, Viral↗

The effect of 6-mercaptopurine on delayed hypersensitivity in guinea pigs.

The development of tuberculin hypersensitivity in guinea pigs after BCG stimulation was suppressed by intramuscular administration of 50 mg/kg/day of 6-mercaptopurine started at the time of stimulation. Fasting of guinea pigs after BCG stimulation had no effect on the development of tuberculin hypersensitivity.

Animals↗

Cytotoxicity mediated by soluble antigen and lymphocytes in delayed hypersensitivity. 3. Analysis of mechanism.

The cytopathic effect of lymph node cells from tuberculin-sensitized rats on rat embryo fibroblasts in the presence of PPD was not enhanced by admixture of normal (nonsensitized) lymph node cells. Preincubation studies showed that this in vitro response is initiated by the reaction of lymphocytes with specific antigen, beginning within 30 min, rather than uptake of antigen by the fibroblasts. The supernatant fluids from suspensions of sensitized cells incubated with PPD for 17 hr or more possessed cytotoxic activity. The target fibroblasts showed a marked increase in acid phosphatase content within 48 hr after the addition of sensitized lymph node cells and antigen.

Acid Phosphatase↗