| Transfer factor (TF) is produced by T lymphocytes, with a small molecular weight and chemically being complex of small peptide and oligonucleotide. TF can transfer donor's cell mediated immunity to receptor's cell mediated immunity. Particularly unspecific TF can enhance receptor's natural immunity and specific immunity, which makes TF being applied at large in treatment and prevention of animal and human diseases. So clarification of cellular and molecular mechanism of TF as enhancer for canine immune function will definitely contribute abundant theoretic evidences and instructions to control of canine diseases, especially canine infectious diseases. In this present study, the requisite swine TF and canine TF were prepared firstly. Afterwards, a range of hybrid shepherd dogs were selected to determine the canine lymphocytic proliferation effects in different time after the dogs were injected with swine TF and canine TF, respectively, the changes of subgroup T lymphocytes, by the methods of lymphocytic transfer proliferation MTT and flow cytometry. The results were as follows: 1. The prepared swine TF and canine TF showed resemble physical and chemical properties, and the trial products of TF met the same level as in the world and can be materials of this study. 2. Effects of FCS,PBMC,PHA-P of different concentration on promote lymphocytes proliferation was tested by MTT test. The result of experiment demonstrate that the best levels combination of canine lymphocyte,calf blood serum were 5×106 unit/mL, 10% respectively. In the lymphocytic transfer test, PHA-P at dosage of 12.5μg/mL performed facilitation effects for canine lymphocytic proliferation (p>0.05). ConA at 0.5~2.5μg/mL markedly proliferated T lymphocytes (p<0.05), with the best effect at 2.5μg/ mL. 3.When being combined with PHA-P and ConA respectively, Homogeneous and heterogeneous TF can both stimulate canine lymphocytic proliferation, but the dose range to facilitate canine lymphocytes significantly proliferating has a few differences. Within 6~10 days after heterogeneous TF was injected, the proliferation ability of canine lymphocytes became stronger and stronger. Also within the 6~10 days, in the dogs injected with heterogeneous TF, the proliferation of lymphocytes, once again stimulated by TF itself or by TF and mitogen, showed a downtrend in the first 4~6 days and then was inhibited after 6 days. 4. With regard to enhancement of the number of lymphocyte in canine peripheral blood of homogeneous TF and heterogeneous TF, the increased were mainly CD4+ T-cells, according to the analysis of the ratio of CD4+/CD8+. CD4+ T-cells had increased for 20 days since the employed dogs were injected with homogeneous TF and heterogeneous TF, respectively. And the enhancive effect of homogeneous TF was better than that of heterogeneous TF. So it can be concluded here that either homogenous or heterogeneous TF can markedly enhance canine cellular mediated immunity, which put forward certain powerful experimental evidences and instructions for control of canine diseases especially canine infectious diseases and for enhancement of immune effects of canine vaccines.
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