ANTIGEN DIRECTION OF SPECIFIC T-CELL CLONES INTO GINGIVAL TISSUES

This study was performed to investigate T-cell traffic to periodontal tissues during infection with a periodontal pathogen Actinobacillus ac tinomycetemcomitans (Aa). Rowett rat T-cell clones, A3 (CD4(+) CD8(-), alpha beta TCR+, NKRP-1(-), specific to Aa) and G2 (CD4(-) CD8(-), al pha beta TCR+, NKRP-1(+), which reacts to Aa, Gram-negative and -posit ive bacteria), both expressed the same prominent adhesion molecules (L FA-1, VLA-4) to the same extent. Binding of bath T-cell clones to rat endothelial cells in vitro was blocked by antibody to VLA-4. Rowett ra ts were infected with Aa and infused with Aa-stimulated, isogenic T-cl one lymphocytes that had been labelled in vitro with (125)IUdR. Radioa ctivity associated with recovery of clone A3, but not G2, was signific antly elevated in the gingivae of infected rats, suggesting migration to infected animals' gingival tissues. Migration of radioactive Aa-spe cific A3 clone cells traced by autoradiography reached a maximum at 24 hr (1.2% of total lymphocytes as radiolabelled cells in infected ging iva versus 0.6% in non-infected), indicating an apparent antigen-direc ted retention in infected rats' gingival tissues. The G2 clone was not retained in the gingival tissues (0.20% of total lymphocytes as radio labelled cells in infected gingiva versus 0.26% in non-infected). Howe ver, the possibility of A3 retention directed by inflammation or tissu e-selective homing could not be excluded. In further experiments, othe r adoptively transferred T-clone lymphocytes [clones G23 (Th1) and F13 (Th2)] with specificity for the 29 000 MW outer membrane protein of A a with the same prominent adhesion molecules could be recovered from r at gingivae previously challenged with this antigen. However, transfer red T-clone lymphocytes [clone G26 (Th1)] with specificity for a diffe rent Aa antigen were not recovered. Therefore, the dynamics of cell en try into periodontal lesions vary for activated T lymphocytes with dif ferent antigenic specificities, indicating the significance of antigen in lymphocyte traffic to periodontal tissues.