Regulation of T-cell sensitization at epithelial surfaces in the respiratory tract: suppression of IgE responses to inhaled antigens by CD3+ TcR α-/β- lymphocytes (putative γ/β T cells).

Repeated exposure of Brown Norway rats to an aerosol of ovalbumin (OVA) induced a state of antigen-specific immunological tolerance, particularly in the IgE isotype. Tolerance was transferable to naive syngeneic animals by inoculation of splenic T cells from tolerant rats. Sequential depletion of tolerant spleen cells by sorting techniques prior to adoptive transfer, employing T-cell subset-specific monoclonal antibodies, indicated that the cells mediating tolerance were CD3⁺, CD4 , CD5⁺ and CD8⁺, but lacked α or β chains in the T-cell receptor (TcR), suggesting that they may be part of the γ/δ T-cell lineage. Consistent with this suggestion, the sorted population demonstrated considerable enrichment for TcRγ chain-specific mRNA. As few as 2 × 10³ cells are sufficient to adoptively transfer tolerance in 200-g adult rats in this model. [ABSTRACT FROM AUTHOR]