Objective: Immunotoxin rRTA:DS27, which was prepared by conjugating DS27 with recombinanl ricin a chain, was compared with ricin:DS27 as immunotoxins. Methods: System analysis were performed regard to their cell-specific cytotoxicity, inhibition on the proliferation of hemoapeutic potential cells, immunogold-labelled intracellular routing and effect of NH_(4)Cl on the cytotoxicity. Results: Results showed that rRTA: DS27 got a more specific cytotoxicity and a weaker inhibition on the proliferation of hemoapeutic potential cells than ricin:DS27, NH_(4)Cl could obsolutelyy enhence the cytotoxicity of rRTA:DS27. Conclusion: rRTA:DS27 had more advantages than ricin: DS27 as immunotoxins.

The key to killing target cells by immunotoxin depends on the specific recognition of antibody to target cell and the cytotoxic effect of toxin. The comparative study of the killing effects of two anti-T immunotoxins, CD5:Ricin and CD5:rRA, on target cells was performed. The elimination rate of immunotoxins was analysed by flow cytometry and MLR. The effect of immunotoxins on the proliferation of hematopoiesis was evaluted by CFU-GM. The results showed that (1) CD5(+) T cells were eliminated and CD25(+) CD3(+) activated T cells were concentration-dependently inhibited by the two immunotoxins in the range of 10(-9) - 10(-11) mol/L; (2) both immunotoxins significantly inhibited the mixed lymphocyte reaction, and the inhibiting effect of CD5:rRA to T cell proliferation was markedly lower than that of CD5:Ricin in the range of 10(-10) - 10(-11) mol/L; (3) the combination of CD5:rRA with 10 mmol/L NH(4)Cl increased the T cell elimination rate; and (4) the two immunotoxins and the combination of NH(4)Cl and CD5:rRA did not suppressed proliferation of granulocyte-macrophage progenitors in the range of concentrations with killing effect. It was concluded that T cell and activated T cell could be eliminated effectively by immunotoxins, the proliferation of granulocyte-macrophage progenitor was not inhibited significantly.