Duck lymphocytes. IV. Collective effects of mitogens

Duck (Anas platyrhynchos) blood lymphocytes were cultured in the presence of phytohaemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM), lentil lectin (LL), Roman snail lectin (HP), wheat germ agglutinin (WGA), Bandeiraea simplicifolia seed lectin (BSS), peanut agglutinin (PNA), horseshoe crab lectin (HSC) and bacterial lipopolysaccharide (LPS). Mitogens were used individually, in pairs, and in multiple combinations. Some pairs resulted in synergism; transformation, assessed by uptake of [3H]thymidine, was much greater than a direct addition of the effects of the two mitogens used separately. Best results were obtained when PHA or LL were paired with a second mitogen. In general, combinations of lectins at slightly suboptimal concentrations gave highest transformation, and all strongly synergistic combinations elicited a similar pattern of dose response through different concentrations of PHA. If a third mitogen was included, some combinations gave some further synergism, in other combinations the synergism of two mitogens was reduced by including a third, and if a pair of mitogens did not demonstrate synergism then none was generated when a third mitogen was included. Inclusion of more mitogens to successfully synergistic trios reduced transformation. The system could provide a useful model for in vitro enhancement of responses among lymphocytes from a species with a weak immune system.