RESUMEN
The supernatants of peripheral blood lymphocytes of tuberculin-sensitive guinea pigs incubated with PPD were investigated using macrophage and leukocyte migration inhibition tests. Inhibition as well as stimulation of cell migration were observed. The effect upon migration cultures seemed to be dependent upon the immunological state of the host; animals of the V-group (vaccinated once without challenge) showed inhibitory activity to both macrophages and leukocytes, while those in the VC-group (vaccinated and challenged) had stimulatory activity only to leukocytes. The addition of antithymocyte serum stopped all activity (macrophage and leukocyte inhibition and leukocyte stimulation), suggesting that thymus-dependent lymphocytes are necessary for such activity.