CHARACTERISTICS OF LYMPHOCYTE-T CELL-LINES ESTABLISHED FROM NIH MINIPIGS CHALLENGE INOCULATED WITH TRICHINELLA-SPIRALIS

MHC restricted, antigen specific, cytokine dependent T-cell lines were established from peripheral blood mononuclear cells (PBMC) of NIH minipigs that were challenge inoculated with Trichinella spiralis. Swine lymphocyte antigen (SLA) inbred NIH minipigs of the SLA(a/a) (aa) haplotype can be divided into Responder (R) and Non-responder (NR) phenotypes on the basis of their ability to destroy encysted muscle larval (ML) forms of the parasite T spiralis. When orally inoculated with 300 infectious ML and challenge inoculated with 10 000 ML, R pigs are able to mount an immune attack against encysted ML resident in host muscle cells since the primary inoculation. Because T-lymphocyte mediated mechanisms are likely to be operative in this response, a series of T-lymphocyte cell lines was established from PBMC of ten aa minipigs 1 0 days after the challenge infection with T spiralis. These t-lymphocyte lines showed antigen specific, cytokine dependent proliferation in response to T. spiralis antigen stimulation. T-lymphocyte cell lines from R and NR pigs were compared and found to be similar in the magnitude of proliferative responses, in the duration of antigen specificity, and in the alterations in T-lymphocyte subsets and cell surface phenotype after antigen stimulation. In vitro antigen stimulation of T-lymphocyte cell lines and evaluation of small lymphocytes and lymphoblasts by density gradient centrifugation, immunofluorescent staining and flow cytometry, revealed that up to 55% of the cells were lymphoblasts at 4 days after stimulation, and that the majority of the lymphoblast population expressed CD4 and CD8, as well as the interleukin-2 receptor and the Class II alloantigen, SLA-DR (DR + ). These results indicate that pig T-lymphocytes of the CD4+CD8+ phenotype may be involved in the anamnestic cell mediated immune response to T. spiralis.