CHARACTERIZATION OF RAT CD4 T-CELL CLONES SPECIFIC FOR THE MAJOR SURFACE GLYCOPROTEIN OF PNEUMOCYSTIS-CARINII

Pneumocystis carinii are coated by abundant heterogenous major surface glycoproteins (MSGs), which facilitate interaction with the host. We have produced MSG-specific T-cell clones from the spleens of P, carini i-exposed Lewis rats and analyzed five for antigen specificity to nati ve MSG and a recombinant form of MSG, cell surface markers, and cytoki ne profiles. All five of the clones were CD4+. All of the clones proli ferated specifically to both the native MSG and the recombinant MSG on ly in the presence of antigen presenting cells demonstrating that the response is antigen/driven rather than mitogen/driven. All five of the clones secreted IL-2 and IFN-gamma, although in differing amounts, im plicating a Th1 response. Only one of the clones produced any detectab le IL-4. This is the first report of T cell clones responsive to a spe cific antigen of P. carinii, MSG. We conclude that the T cell clones w ill be helpful in mapping protective epitopes present in MSG and in fu nctional studies of MSG.