PATTERNS OF INFLAMMATORY RESPONSES FOLLOWING RECHALLENGE OF SKIN LATE-PHASE ALLERGIC REACTION SITES

Background: Previous studies have suggested altered responses to repea t skin tests in the sites of IgE-mediated late-phase reactions (LPRs) induced within the previous 48 hours, To explore the possible modulati on of LPRs in such rechallenge sites, we compared inflammatory respons es in skin chambers induced over previous LPR and control sites. Metho ds: Skin blisters were induced and unroofed in 12 human subjects over two sites of previous LPRs induced by intradermal injection of pollen antigens 24 hours or 48 hours earlier and two sites previously injecte d with buffer diluent (B), Skin chambers containing the same antigens were appended to one intradermal antigen site (called Ag/Ag) and one i ntradermal B site (B/Ag), and B-containing chambers were placed over a ntigen (Ag/B) and B (B/B) intradermal sites. Fluids were collected aft er the first and the second through fifth hours of challenge. Results: In skin chamber challenges 24 hours after the intradermal injection, there was no significant difference after the first hours between the Ag/Ag or B/Ag sites in either histamine or tryptase levels; both were significantly higher than at Ag/B or B/B sites (p < 0.01), The same pa ttern of events was seen in fluids obtained from the second through fi fth hours. The same pattern of findings was seen in examination of lev els of the total leukocyte accumulation, total eosinophil accumulation , and frequency of activated (EG(2)+) eosinophils. Levels of lactoferr in, released from activated neutrophils, and eosinophil cationic prote in, released from activated eosinophils, were also similar at Ag/Ag an d B/Ag sites; both mere significantly higher than at B/B sites, wherea s levels at Ag/B sites were intermediate between those found at B/Ag a nd B/B sites. The pattern of events in skin chamber challenges 48 hour s after intradermal injection was similar to that seen at 24 hours, ex cept that levels of inflammatory mediators/cells in Ag/B sites were mo re intermediate between the B/Ag and B/B sites. Conclusion: There is n o significant alteration of mediator or inflammatory cell responses af ter antigen rechallenge of previous LPR sites when compared with those found in antigen challenge of non-LPR sites.