Leukocyte Aggregation: An in Vitro Assay for Cell-Mediated Immunity

Abstract

Abstract An in vitro leukocyte-aggregation assay was developed to assess cell-mediated immune reactivity by hosts against their allotransplants. The assay, which measures the adhesion of host leukocytes to target cells, is caused by a specific recognition of donor antigens by sensitized lymphocytes. The formation of aggregates may reflect the release of chemotactic and migration inhibition factors following recognition of specific target cell antigens, thereby attracting nonimmune bystander cells to the reaction foci. The test is simple to perform, brief, and requires small amounts of materials. Analysis of the patterns of reactivity of host cells suggests that the immunological specificity of the recognition event is consistent with the HL-A system in 80% of cases. Instances of disparities between predicted and observed reactions were attributed to lack of host sensitization, differences between serological and cellular HL-A cross-reactivities, and the potential participation of other histocompatibility systems.