Distinct in vivo and in vitro cytokine profiles of draining lymph node cells in acute and chronic phases of contact hypersensitivity: Importance of atype 2 cytokine-rich cutaneous milieu for the development of an early-typeresponse in the chronic phase

Although regional lymph nodes (LN) have been extensively studied as rich so urces of effector T cells in contact hypersensitivity (CH), it remains unkn own whether T cell responses in the LN reflect those in effector skin sites . We previously showed that repeated elicitation of CH results in a shift i n the time course of Ag-specific CH from a delayed-type hypersensitivity re sponse to an early-type response, a reflection of a shift in cutaneous cyto kine expression from a type 1 to a type 2 profile. To investigate whether r epeated elicitation of CH could also drive T cell development to the type 2 phenotype in the regional draining LN, sequential cytokine gene expression after hapten application was assessed during both the acute and the chroni c phase of CH. In the draining LN the shift to type 2 cytokine production w as also observed, but more mixed patterns of responses were induced than in the corresponding skin sites. The chronic LN cells (LNC), when stimulated in vitro, produced markedly lower levels of type 1 cytokines and higher lev els of type 2 cytokines than the acute LNC, A successful passive transfer o f an early-type response by the LNC was only induced in the recipient mice when the skin sites chronically treated with hapten were elicited. These re sults indicate that an early-type response by regional LNC would take place only in a milieu with sufficient levels of type 2 cytokines.