Localized antigen challenge of the nasal mucosa.

We describe a localized nasal antigen challenge and the measurement of mediators found at the same site. Eight ragweed-allergic subjects were challenged on 2 days, 1 week apart. Challenges consisted of six sequential provocations, beginning with two control challenges (diluent for antigen-phenol-buffered saline) followed by four increasing antigen doses (0.6, 6, 60, and 160 protein nitrogen units) (antigen day) or an additional four control challenges (control day). The number of sneezes and the symptom scores increased significantly with increasing antigen doses. The levels of histamine and N-alpha-tosyl-L-arginine methyl ester-esterase activity increased in the eluted secretions on the antigen day, but not on the control day. The amount of secretions collected also increased per unit of time on the antigen day. We found no significant increase in the concentration level of either histamine or N-alpha-tosyl-L-arginine methyl ester-esterase in nasal secretions on either day. We conclude that the total amount of histamine and N-alpha-tosyl-L-arginine methyl ester-esterase activity increased per unit of time while their concentration did not.

The effect of a leukotriene antagonist on the early response to antigen.

The sulfidopeptide leukotrienes (LT) C4, D4, and E4 increase in nasal secretions during the nasal response to antigen challenge, and nasal challenge with LTD4 induces nasal congestion. To further assess the role of leukotrienes, we administered an oral LTD4 antagonist, L-649,923, to 12 patients who had nasal allergy to grass and ragweed pollen, in a double-blind, placebo-controlled, crossover study. Patients were challenged intranasally with increasing doses of pollen on each of 2 days, and the recovered nasal lavage fluids were assayed for histamine, TAME-esterase activity, and immunoreactive LTC4/D4/E4. The patients graded runny nose, congestion, and throat irritation, and sneezes were counted. Significant (p less than 0.01) increases in all parameters were found when comparing antigen challenge with diluent challenge, but no differences were seen among the treatment groups. Thus, oral L-649,923 was not effective in blocking the symptoms of the early nasal allergic response.

Involvement of basic amino acids in the activity of a nucleic acid helix-destabilizing protein.

Under conditions of low ionic strength, ribonuclease A, which binds more tightly to single- than to double-stranded DNA, lowers the melting temperature of DNA helices (Jensen and von Hippel (1976) J. Biol. Chem. 251, 7198-7214). The effects of chemical modification of lysine and arginine residues on the helix-destabilizing properties of this protein have been examined. Removal of the positive charge on the lysine epsilon-amino group, either by maleylation or acetylation, destroys the ability of RNAase A to lower the Tm of poly[d(A-T)]. However, reductive alkylation of these residues, which has not effect on charge, yields derivatives which lower the Tm by only about one-half that seen with unmodified controls. Phenylglyoxalation of arginines can largely remove the Tm-depressing activity of RNAase A. RNAase S, which is produced by cleavage of RNAase A between amino acids 20 and 21, possesses DNA helix-destabilizing activity comparable to that of the parent protein, whereas S-protein (residues 21-124) increases poly[d(A-T)] Tm and S-peptide (1-20) has no effect on Tm. These results suggest that specific location of several basic amino acids situated on the surface of RNAase A is largely responsible for this protein's DNA melting activity.