Chapter 26 Nasal provocation and pulmonary function tests

Abstract

Priming is based on the observation that the dose of intranasal pollen needed to cause a repeated nasal allergic reaction decreases if challenges are carried out on a daily basis. For example, on day 1, 10,000 pollen grains are required; on day 2, 1000 pollen grains arc required; and so on. Some mediators in nasal wash increase in primed subjects during successive challenges. Immediate nasal responses include increases in histamine, prostaglandin (PC) Dz, chemotactic factors, TAME esterase, and leukotriene C,. PGD, is a major mast cell product but is not generated by basophils. Additional mast cell activation is thought to occur after successive antigen challenges. A late reaction may occur 3 to 11 hours after initial challenge and may be more or less intense than the early reaction. Histamine, TAME esterase (can generate kinins), and leukotrienes occur in late and early reactions. Major basic protein is found in the late reaction, but PGD, is not. Some evidence suggests that histamine in the late reaction is from basophils, not from Imast cells. If antigen is readministered after the end of the late reaction, PGDz is detected. suggesting production and release by mast cells in the next early (immediate) nasal reaction. Topical steroids (1 week pretreatment) inhibit late nasal reactions to allergen (like oral steroids) plus the immediate reaction. Immunotherapy can inhibit the early and late nasal responses to allergen challenge; this differs from bronchial reactions in patients with asthma, in whom the late but not early response can be suppressed.