Immunotoxin depletion of T cells and its effect on hematopoietic progenitor cells in human cord blood.
OBJECTIVE
To study the selective toxicity of immunotoxin (IT) on T cells in cord blood and simultaneously determine its effect on hematopoietic progenitor cells.


METHODS
The percentage of CD5 and CD8 T cell subsets in cord blood (CB) and bone marrow (BM) as well as peripheral blood (PB) was measured by immunoenzymatic labeling of monoclonal antibodies using immune complexes of alkaline phosphatase and monoclonal anti-alkaline phosphatase (APAAP complexes). One-way mixed lymphocyte cultures (MLC) were performed to compare the proliferative response of CB with that of PB. The proliferative capability of cord blood T cells and T lymphocyte transformation capacity were evaluated in the presence of anti-CD8 or anti-CD5 immunotoxin by one-way MLC and colorimetric MTT (tetrazolium) assay, respectively. The effect of IT on the growth of hematopoietic progenitor cell of colony forming unit-granulocyte and macrophage (CFU-GM), burst forming unit-erythroid(BFU-E), multipotential hemotapoietic progenitors (CFU-Mix) from CB were estimated by colony-forming assays.


RESULTS
A certain proportion of CD5 and CD8 T cells existed in CB. The alloproliferative capacity of CB was similar to that of PB. CD5: Ricin at a dosage of 1 x 10(-10)-1 x 10(-8) mmol/L and CD8: Ricin concentration in the range of 1 x 10(-9)-1 x 10(-8) mmol/L effectively decreased both the proliferative capability of T cells in MLC during CB and T cell transformation. Over the dosage of 1 x 10(-10)-1 x 10(-9) mmol/L, both kinds of IT didn't obviously affect the growth of hematopoietic progenitor cells.


CONCLUSIONS
CD5: Ricin and CD8: Ricin may effectively deplete T cells and may not significantly inhibit the function of hemaptopoietic cells at a specific dosage.
Xu
M
M
Department of Pediatrics, General Hospital of Guangzhou Military Area, Guangzhou 510010, China.
Lu
S
S
Shen
B
B
Li
Y
Y
D018956:CD5 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D005312:Fetal Blood / Q000276:immunology*; D006086:Graft vs Host Disease / Q000209:etiology; D006412:Hematopoietic Stem Cells / Q000187:drug effects*; D006801:Humans; D000922:Immunotoxins / Q000494:pharmacology*; D008213:Lymphocyte Activation; D008212:Lymphocyte Depletion; D012276:Ricin / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000187:drug effects*
D018956:CD5 Antigens; D016827:CD8 Antigens; D000922:Immunotoxins; D012276:Ricin