DLA-D-specific suppressor cells characterized by monoclonal antibodies

Abstract

Canine lymphocytes alloantigen-primed in mixed leukocyte culture (MLC) were tested for their ability to suppress MLC reactivity. These cells were added to fresh responder cells in MLC at ratios of 1:50 and 1:20 and suppressed reactivity 90±7% (mean ± 1 SD) and 91±3% respectively. At lower ratios no suppression was observed. Monoclonal antibody E11 (IgG3) recognized a subset of canine Thy1+ T cells, and with complement treatment was capable of depleting suppressor cells from bulk MLC (11±6% of control suppression), but DT-2 (IgG2a), another canine T-cell antibody, had no such effect (84±11%) (P=0.028). Antibody A5 (IgG2b), reactive with all T and most non-T cells, also eliminated suppression...