In vitro studies of the effect of MAb NDA 4 linked to toxin on the proliferation of a human EBV-transformed lymphoblastoid B cell line and of gibbon MLA leukemia cell line.
The rejection of allografts is mediated by cytolytic T cells and antibody-secreting B cells. Selective ablation of these activated cells from peripheral blood lymphocytes may offer a a method of controlling allograft rejection. An immunotoxin was prepared from the monoclonal antibody (mAb) NDA 4, which recognizes a differentiation antigen (NDA 4) common to activated B and T cells. MAb NDA 4 was conjugated to the ribosome-inhibiting protein gelonin via a cleavable disulfide bond provided by a crosslinking reagent. The purified immunotoxin was evaluated for in vitro cytotoxicity on NDA 4 positive T and B cell lines. Conjugation of mAb NDA 4 to gelonin increased the in vitro cytotoxicity by a concentration factor of 1000, compared to gelonin alone. The specificity and saturability of mAb NDA 4 binding, as well as the number of antigenic sites per cell on resting versus activated T lymphocytes, were also evaluated. Resting T cells expressed 400-800 sites per cell. PHA-activated T cells and the MLA T cell leukemia expressed 10,000 to 80,000 sites per cell. Peripheral blood mononuclear cells obtained from allografted baboons in quiescence or undergoing rejection were compared for NDA 4 expression by flow cytometry. Lymphocytes obtained from baboons rejecting a heart allograft expressed NDA 4, whereas transplant recipients in quiescence showed no detectable NDA 4. These results suggest that mAb NDA 4-derived immunotoxins may be valuable for the selective depletion of activated lymphocytes while sparing the resting population.
Harris
P
P
College of Physicians & Surgeons of Columbia University, Department of Pathology, New York, NY 10032.
Reed
E
E
King
D W
DW
Suciu-Foca
N
N
D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D000915:Antibody Affinity; D000918:Antibody Specificity; D000943:Antigens, Differentiation / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D015153:Blotting, Western; D002460:Cell Line; D002472:Cell Transformation, Viral; D003602:Cytotoxicity, Immunologic; D006084:Graft Rejection; D016027:Heart Transplantation / Q000276:immunology; D004854:Herpesvirus 4, Human; D006922:Hylobates; D000922:Immunotoxins / Q000494:pharmacology*; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D010940:Plant Proteins / Q000008:administration & dosage; D054789:Ribosome Inactivating Proteins, Type 1; D013045:Species Specificity; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D000922:Immunotoxins; D010940:Plant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; C025674:GEL protein, Gelonium multiflorum