Elevated serum concentrations of IgE antibodies to environmental antigens in HIV-seropositive male homosexuals.

Forty-five homosexual male subjects with human immunodeficiency virus (HIV) infection, who received care during a 4-month period in an ambulatory center for acquired immunodeficiency syndrome (AIDS), were classified according to their principal presentation with characteristic secondary infections (CDC group IV C, N = 28), cancers (IV D, N = 10), or limited or no symptoms (groups II, III, IV A, or IV B, N = 7). The incidence of allergic rhinitis and conjunctivitis increased after HIV seroconversion by approximately twofold in patients of groups IV C and IV D. The mean serum concentration of IgE was significantly higher for group IV C than for the other HIV-seropositive groups and for a control group of 45 HIV-seronegative homosexual male subjects from the same community who were studied concurrently. More patients in groups IV C and IV D had positive RASTs for a panel of environmental antigens than patients in the other HIV-seropositive groups and the HIV-seronegative control group. Patients with AIDS presenting with typical secondary infections thus have a high frequency of some clinical and laboratory manifestations of allergic diseases.

Mediation of prolonged increases in nasal mucosal blood flow by calcitonin gene-related peptide (CGRP).

Calcitonin gene-related peptide (CGRP) is a vasoactive and smooth muscle contractile neuropeptide, which is released during human nasal allergic reactions. Mean values for nasal blood flow (NBF), quantified in each nostril by a laser Doppler technique, varied no more than +/- 25% of a mean initial reading in normal human subjects over 4 hr in a controlled environment. Intranasal administration of multiple doses of CGRP to 17 normal subjects stimulated significant mean increases in NBF at 30-1000 ng of CGRP, with maximal mean rises of 86-130% after 100 and 300 ng of CGRP. Delivery of incremental doses of CGRP every 30 min for 2 hr evoked repetitive responses without tachyphylaxis. A single vasoactive dose of CGRP, which achieved nasal fluid concentrations similar to those elicited by antigen challenge, elicited the sensation of nasal obstruction in most subjects at 1 hr and for up to 4 hr after CGRP, without elevating nasal fluid concentrations of histamine. CGRP thus is a potent histamine-independent mediator of allergic reactions.

Suppression by ingested eicosapentaenoic acid of the increases in nasal mucosal blood flow and eosinophilia of ryegrass-allergic reactions.

Nasal mucosal blood flow, assessed by a laser Doppler probe technique, and the concentration of eosinophils in nasal secretions were quantified during challenge of one nostril with ryegrass-pollen antigen and the other nostril with diluent alone in seven patients with ryegrass-allergic rhinitis. The identical studies were repeated after an 8-week course of 3.5 gm/day of eicosapentaenoic acid (EPA). Ryegrass antigen evoked mean rises in nasal blood flow of 30% to 100% after 10 and 30 minutes that were significant, relative to prechallenge levels and to levels after diluent challenge, both before and after EPA. Antigen-induced increases in nasal blood flow were significantly less after than before EPA at 10 minutes, and at 180 minutes increases were significant only before EPA. In ryegrass-allergic patients with rhinitis who did not take EPA between the two studies, the increases in blood flow after antigen challenge were the same on both occasions. Similarly, the nasal eosinophilia elicited by antigen was significant at 180 minutes only before EPA. Both a composite index of signs and symptoms and the constituent variables, reflecting the clinical response to antigen challenge, were unaffected by EPA. The suppression by EPA of responses of nasal blood flow and nasal eosinophils to antigen challenge supports a role for fatty acid and phospholipid mediators in allergic rhinitis, but the clinical assessment did not provide evidence for any symptomatic benefit from EPA.

Distinctive patterns of release of neuroendocrine peptides after nasal challenge of allergic subjects with ryegrass antigen.

The concentrations of the neuropeptides substance P, somatostatin, and calcitonin gene-related peptide in human nasal secretions were quantified by radioimmunoassays, concurrently with that of histamine, in the course of nasal challenge of allergic and control subjects with ryegrass antigen to examine contributions of neuromediation of the tissue response. Each of the neuropeptides and histamine were detected in nasal lavage fluid prior to challenge. In allergic patients, but not normal controls, antigen evoked significant increases of 3-fold in histamine at 15-60 min, 1.5- to 4-fold in calcitonin gene-related peptide at 15 min-24 hr, and more than 2-fold in somatostatin at 6 hr, without altering the concentration of substance P in nasal lavage fluid. The identity of the neuropeptides was confirmed chromatographically. Thus calcitonin gene-related peptide may mediate nasal congestion directly and somatostatin may be one of the factors regulating the late involvement of basophils and mast cells in allergic rhinitis.