ADOPTIVELY TRANSFERRED LATE ALLERGIC AIRWAY RESPONSES ARE ASSOCIATED WITH TH2-TYPE CYTOKINES IN THE RAT

Late allergic airway responses can be transferred by CD4(+) T cells in the rat. To investigate the role of T-cell cytokines in these respons es, we examined the expression of mRNA for Th2 (interleukin [IL]-4 and IL-5) and Th1 (IL-2 and interferon gamma [INF-gamma])-type cytokines in Brown Norway rats that were administered either antigen-primed W3/2 5(CD4)(+) or OX8(CD8)(+) T cells. Donors were actively sensitized by s ubcutaneous injection of ovalbumin (OVA) in the neck and T cells were obtained from the cervical lymph nodes by immunomagnetic cell sorting for administration to unsensitized rats. Control rats received bovine serum albumin (BSA) primed CD4(+) and CD8(+) T cells. Two days later, recipient rats were challenged with aerosolized OVA, and bronchoalveol ar lavage (BAL) was performed 8 h after challenge. BAL cells expressin g mRNA for IL-2, IL-4, IL-5, and INF-gamma were analyzed using the tec hnique of in situ hybridization. Recipients of OVA-primed CD4(+) T cel ls had an increase in the fraction of BAL cells expressing mRNA for IL -4 and IL-5 compared with BSA-primed CD4(+) or OVA-primed CD8(+) cells (P < 0.001). Recipients of CD8(+) T cells had an increase in INF-gamm a mRNA expression after OVA challenge compared with recipients of BSA- primed-CD8(+) or OVA-primed CD4(+) T cells (P < 0.001). In conclusion, T-cell-dependent allergen-induced late responses are associated with the expression of mRNA for IL-4 and IL-5, indicating Th2 cell activati on. Furthermore, the increased expression of INF-gamma in allergen cha llenge recipients of antigen-primed CD8(+) T cells suggests that CD8() T cells may be important in modulating allergic responses.