LECTIN-DEPENDENT CELL-MEDIATED CYTOTOXICITY

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Abstract
Alloimmune T lymphocytes kill a wide spectrum of target cells, even in the absence of alloantigen recognition, providing that a lectin is incorporated into the assay medium. The lectin-dependent cell-mediated cytotoxicity (LDCMC) assay was modified to evaluate the cytotoxic activity of canine T cells using a human [Burkitt''s lymphoma] B lymphoblastoid cell line (Raji) as the target. Canine peripheral blood mononuclear cells activated in vitro in mixed leukocyte cultures or by concanavalin A (Con A) killed 51Cr-labeled Raji target cells (up to 70% in 4 h) when Con A was included in the assay. T cells expressed cytotoxic activity only when activated and when Con A was present in the assay. Canine T cells activated in vivo also exerted cytotoxic activity in the LDCMC assay. T cells obtained from a rejecting allografted lung by bronchoalveolar lavage displayed considerably higher cytotoxic activity than did T cells obtained from the contralateral normal lung or peripheral blood of the same dog. T cells from the lungs and blood of normal dogs and lung-allografted dogs without rejection exerted no cytotoxic activity. The LDCMC assay using xenogeneic Raji cells as targets is a valid measure of the cytotoxic activity of canine T cells. Its major advantages include the fact that it is simple to perform and can be used when specific target cells are not available.