Regulation of lymphocyte trapping: the negative trap.

Suppression of 51Cr-labeled lymphocyte homing to the spleen occurs after administration of insoluble protein antigen and as a late sequela to the graft-vs-host response (GVHr). This decrease in splenic localization of labeled cells, termed "negative trapping," has elements of immunologic specificity in that tolerance induction or presensitization abrogates the negative trap. Increasing the dose of antigen accelerates the appearance of the negative trap, which is, however, evanescent, lasting from 24 to 48 hr. Synergistic and antergistic regulation of the GVHr-induced lymphocyte trap is produced by populations of 850 R-irradiated thymocytes and by F1 cortisone-resistant thymocytes. The time at which these subpopulations cause suppression or amplification of the lymphocyte trap correlates with the activity of the GVHr-producing inoculum. These findings suggest that regulation of lymphocyte traffic may provide a mechanism for control of immune responses in vivo.