The mixed leukocyte reaction (MLR) in carp: bidirectional and undirectional MLR responses.

Two-way and one-way mixed leukocyte reaction (MLR) was demonstrated in peripheral blood leukocytes (PBL) of carp. Primary two-way MLR in randomly selected donor pairs were highly variable. Weak primary responses could be strongly augmented by mutual in vivo priming of the reacting donors. One-way MLR was performed using irradiated (16,000 R) allogeneic PBL as stimulators. Reciprocal responses of randomly paired donors were usually unequal, suggesting the usefulness of this method for genetic analysis of MLR-recognized histocompatibility antigens in carp. Kinetics of the primary and secondary two-way MLR were studied, as well as the kinetics of primary one-way MLR against pooled allogenic stimulator cells.