RT-PCR demonstrated that ionotropic (iGluR NR1) and metabotropic (mGluR Group III) glutamate receptors are expressed in rodent lymphocytes. Flow cytometry showed that activation of iGluR NR1 by N-methyl-D-aspartate (NMDA) increased intracellular free calcium and reactive oxygen species (ROS) levels and activated caspase-3. The latter effect was attenuated by the NMDA antagonist, 5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801), by the antioxidant N-acetylcysteine and by cyclosporin A. Treatment with L-2-amino-4-phosphonobutyric acid (L-AP4), an mGluR Group III agonist, increased lymphocyte ROS levels but to a lower extent than did NMDA. Activation of lymphocytes with both NMDA and L-AP4 caused a synergistic increase in ROS levels and induced necrotic cellular death without elevating the caspase-3 activation observed in the presence of NMDA alone. These results show that lymphocyte iGluR NR1 and mGluR Group III receptors may be involved in controlling rodent lymphocyte functions and longevity as they regulate events in cell proliferation, maturation, and death.