Antigen-induced late-phase airway obstruction in the guinea pig?

Hartley or Dunkin-Hartley guinea pigs (n=136) were actively sensitized to ovalbumin orAscaris suum protein by five different regimes. Specific airway resistance (sR_AW) was measured in conscious animals by a plethysmographic procedure before, immediately following and at various intervals (up to 96 h) after aerosolized antigen or vehicle challenge. Each sensitization and challenge regime produced an immediate allergic response with positive responses (defined as a 2-fold increase in sR_AW) in 78–100% of animals. Recovery from the immediate response followed by late-phase responses was observed in only two out of a group of four animals. The results failed to substantiate literature reports of a high incidence of late responses in the guinea pig at 4–8, 17–24 or 72 h after allergen challenge.