Observation of the growth of some adenineless mutants of Schizosaccharomyces pombe on six substituted purine analogs leads to the hypothesis that an enzyme is present which catalyzes the conversion of these analogs into hypoxanthine. The enzyme adenase (adenine aminohydrolase, EC 3.5.4.2) has been found to be active in cell-free extracts of S. pombe. Results are reported which are in agreement with the hypothesis that this enzyme is responsible for the in vivo utilization of 6-chloropurine. This evidence comes mainly from a study of adenine aminohydrolase in two mutants selected for partial inability to grow on 6-chloropurine.

Adenine↗

PubMedDate not supplied

Production of a monoclonal antibody against a major allergen of Dactylis glomerata pollen (Dg1).

A mouse monoclonal antibody was produced against the most frequent allergen Ag Dg1ief, purified from the Dactylis glomerata grass pollen by isoelectric focusing. Using the immunoprint technique, this monoclonal antibody detected Ag Dg1ief in D. glomerata pollen and some cross-reacting molecules in four other grass pollens. This hybridoma was grown in ascitic fluid. An immunosorbent was made from it and, by affinity chromatography, was used to purify monoclonal Ag Dg1m from the pollen extract. Ag Dg1m (6,000 to 8,000 daltons) appeared to be 4 to 5 times smaller than Ag Dg1ief. It appeared as a weak allergen in passive cutaneous anaphylaxis in rats, but was more potent in triggering histamine release on human basophils from grass-pollen sensitive patients. These results suggest that Ag Dg1m could be a part of the Ag Dg1ief used to induce production of this monoclonal antibody.

Animals↗

PubMedDate not supplied

In vitro histamine release from human basophils triggered by a purified allergen from Dermatophagoides farinae: bimodal aspect of the dose response curve.

Histamine release experiments were performed over a 10(6)-fold range of allergen concentrations on basophils of patients sensitive to Dermatophagoides farinae. Two extracts of D. farinae were used, a partially purified one (Df 80d) containing several allergens and a highly purified component (Ag11). This histamine release patterns obtained with the complex allergen mixture Df 80d gave broad histamine release curves presenting an initial increase, followed by a decrease or a plateau, with occasionally a small dip. The Ag11-induced histamine release curves presented two peaks (bimodal pattern), separated by a more or less pronounced inhibition dip. No non-specific histamine releasing activity was observed with the basophils of two controls. The possible theoretical models for the bimodal histamine release patterns are discussed.

Allergens↗