EXPERIMENTAL HYPERSENSITIVITY PNEUMONITIS - EFFECT OF THY1.2(+) AND CD8(+) CELL DEPLETION

We previously demonstrated that recipient CD4(+) cells are necessary f or expression of adoptive murine experimental hypersensitivity pneumon itis (EHP). in contrast, the acute inflammatory response to intratrach eal (i.t.) administration of Micropolyspora faeni (direct EHP) is not CD4(+) cell dependent (Am. J. Respir Crit. Care Med. 1994;149:1288-129 4). To further characterize the cells responsible for development of p ulmonary inflammation in recipient animals, we depleted recipients of either Thy1.2(+) or CD8(+) cells before transfer of M. faeni-sensitize d cultured C3H/HeJ spleen cells and i.t. challenge with M. faeni. We u sed the same depletion technique to determine the contribution of thes e cells to the pulmonary response to i.t. M. faeni in animals that did not receive cultured cells (direct EHP). The nature and extent of pul monary inflammatory changes in these animals were assayed either 4 d a fter i.t. challenge with M, faeni in adoptive EHP or 2 d after i.t. ch allenge with M. faeni in direct EHP; We also tested the hypothesis tha t our previously demonstrated ablation of adoptive EHP caused by admin istration of anti-CD4 antibody was due to depletion of recipient CD4() cells by allowing recovery of recipient CD4(+) cells of anti-CD4-tre ated animals before i.t. challenge. In addition, we allowed Thy1.2(+) cell recovery of anti-Thy1.2-treated animals before i.t. challenge. Cu ltured M. faeni-sensitized spleen cells could adoptively transfer EHP to animals treated with an irrelevant antibody or PBS. Depletion of Th y1.2(+) but not CD8(+) cells ablated the ability of recipient animals to express adoptive EHP. Direct EHP was not affected by depletion of T hy1.2(+) or CD8(+) cells. Animals treated either with anti-CD4 or anti -Thy1.2 antibody and allowed to recover CD4(+) or Thy1.2(+) cells coul d express adoptive EHP. We conclude that the ability to express adopti ve EHP is dependent on the presence of recipient Thy1.2(+) and CD4(+) but not CD8(+) cells. In contrast, the acute inflammatory response to M. faeni is a T cell-independent phenomenon.