[Preparation of placenta factor and its immunoregulatory effects on lymphocytes in vitro].
The study was aimed to establish a new method of preparation of human placenta factor (PF) and to determine its physic-chemical properties, as well as effects on lymphocytes in vitro. PF was prepared by ultrafiltration. The contents and molecular weight of all constitutions were determined by Bradford method and SDS-PAGE, respectively. Cyclosporin A (CsA) was served as positive control, normal saline (NS) was used as negative control. PHA-stimulated lymphocyte proliferation and mixed lymphocyte reaction (MLR) were detected with MTT assay. The expression of CD69 on T cells was analyzed by flow cytometry. Cytotoxicity of natural killer (NK) cells against K562 tumor cells was examined with LDH release assay. The results indicated that PF was determined to be a group of low molecular weight polypeptides, consisting of two major components whose molecular weight were 9.187 and 4.794 kD respectively. The contents of PF were 5.7 - 6.9 mg/g fresh placenta. PF had similar suppressive effects on PHA-stimulated lymphocyte proliferation and MLR in vitro as compared with CsA (P > 0.05). Both PF and CsA could downregulate the expression of CD69 on T cells which had been stimulated by PMA plus ionomycin (PF vs CsA, P > 0.05). The cytotoxicity of NK cells against K562 cells in PF group was slightly higher or equivalent as compared with that in NS group (P > 0.05), but the cytotoxicity in CsA group was much lower than that in NS group (P < 0.05). It is concluded that a new method of preparation of PF has been established. This study first demonstrates that PF has strong immunosuppressive effects on T cell in vitro, and suppresses T cell proliferation and activation induced by mitogen and alloantigen. This study indicats that PF has no any inhibitory effects, but even enhances the cytotoxicity of NK cells against K562 tumor cells. These results suggest that PF may have suppressive effects on graft-versus-host disease (GVHD) without diminishing graft-versus-tumor (GVT) effects. Therefore, PF may probably be an ideal and promising agent against GVHD.
Yan
Chen-Hua
CH
Peking University People Hospital, Peking University Institute of Hematology, Beijing 100044, China.
Lu
Dao-Pei
DP
D016572:Cyclosporine / Q000494:pharmacology; D005293:Ferritins / Q000276:immunology* / Q000302:isolation & purification; D006086:Graft vs Host Disease / Q000378:metabolism / Q000517:prevention & control; D006801:Humans; D007166:Immunosuppressive Agents / Q000276:immunology*; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology*; D010088:Oxidoreductases; D013601:T-Lymphocytes / Q000276:immunology*
D007166:Immunosuppressive Agents; D016572:Cyclosporine; D005293:Ferritins; C454461:FTH1 protein, human; D010088:Oxidoreductases