Isolation of human suppressor T cells by peanut agglutinin

Peanut agglutinin (PNA) is a plant lectin which has been used for the separation of suppressor T cells in mice. The present study was carried out to determine whether PNA would be useful in the isolation of human suppressor T cells. Normal human peripheral blood mononuclear cells (PBMC) were activated by concanavalin A (Con A) and the resultant blastoid cells were then incubated with PNA-coated autologous erythrocytes to induce the rosette formation. The PNA rosette-forming cells (15-18% of Con A-activated PBMC) were separated from non-rosette-forming cells by differential centrifugation. The rosette-forming cells suppressed pokeweed mitogen-induced polyclonal immunoglobulin synthesis by 2- to 5-fold. This degree of suppression was greater than that seen with non-rosette-forming cells or with unseparated Con A-activated cells. Our data indicate that PNA rosette fractionation provides a simple and useful method for the isolation of human suppressor T cells.