Donor MHC gene to mitigate rejection of transplantation in recipient mice.

BACKGROUND: Donor organ rejection continues to be a significant problem for patients receiving transplants. We therefore tested whether transferring a donor's major histocompatibility complex (MHC) gene to the recipient would mitigate the rejection of transplanted hearts in mice. METHODS: H-2K(k) gene from donor mice was amplified using nested polymerase chain reaction (PCR) and ligated into a mammalian expression vector, which was then transfected into thymus ground mass cells collected from the recipients. Clones stably expressing the transgene were then injected into the recipients' thymus visualized using ultrasound. Control mice were administered cells previously transfected with empty vector. Following heart transplantation, cardiac activity was monitored electrocardiographically. Recipient thymus cells were tested for MHC antigenicity using flow cytometry and spleen cells were subjected to mixed lymphocyte culture tests. Finally, the transplanted hearts were sectioned, stained and examined under light microscopy. RESULTS: Southern analysis following nested PCR revealed clear expression of H-2K(k) gene. Following transplantation, electrocardiosignals were detectable highly significantly longer in recipients administered thymal cells expressing donor H-2K(k) than in those receiving control cells. Flow cytometric analysis using an anti-H-2K(k) antibody confirmed its expression in H-2K(k) treated recipients but not in control mice. Mixed lymphocyte cultures containing H-2K(k) treated cells showed significantly less proliferation than those containing control cells. Hearts from control mice showed substantially greater lymphocyte infiltration than those from H-2K(k) treated mice and large areas of necrosis. CONCLUSION: Rejection of transplanted hearts can be mitigated substantially by introducing the donor's MHC into the recipient.

[Excitatory postsynaptic potential evoked by stimulation of the ventrolateral region of the cerebellum in crucian carp Mauthner cell].

In the present experiments, the characteristics of the electrical responses to stimulation of the cerebellum in crucian carp Mauthner cell were explored with microeletrode intracellular recording technique. A composite excitatory postsynaptic potential (cerebellum-evoked EPSP) could be induced from the soma, the ventral dendrite and the proximal end of the lateral dendrite in crucian carp Mauthner cell (M-cell) on either side by stimulation of the ventrolateral region of the cerebellum. The cerebellum-evoked EPSP presented characteristics of relatively short latency (0.63+/-0.09 ms), longer duration (5.49+/-1.13 ms), graded amplitude and dependence on stimulation frequency. Stimulation of the cerebellum with higher intensity always activated the M-cell orthodromically. Multiple intracellular recordings showed that the cerebellum-evoked EPSP originated in the distal end of the ventral dendrite. The results suggest that the cerebellum-M-cell pathway is probably composed of a group of neuron chains with different numbers of synaptic relays projecting to the distal end of the ventral dendrite in order of length of the chains.