Activation of T lymphocytes for adhesion and cytokine expression by toxin-conjugated anti-CD3 monoclonal antibodies.
BACKGROUND
Immunosuppressive drugs that target T cells are useful for prolonging allograft survival. The anti-CD3 immunotoxin FN18-CRM9 has been shown to effectively prolong renal allograft survival in a rhesus monkey model of transplantation. However, immunotoxin-treated monkeys showed increased levels of inflammatory cytokines and produced antibodies to donor proteins. To better understand the role of FN18-CRM9 in the production of cytokines and anti-donor antibodies in the monkey model, we examined whether this immunotoxin elicits functional responses in T cells.


METHODS
Purified normal rhesus monkey T cells (>98% purity) were incubated with immunotoxin FN18-CRM9 or the unconjugated anti-CD3 monoclonal antibodies and then examined for changes in protein tyrosine phosphorylation, adhesion to fibronectin, gene expression, and proliferation in the presence or absence of anti-CD28 monoclonal antibodies (mAb) and interleukin-2.


RESULTS
Immunotoxin treatment of T cells in vitro increased protein tyrosine phosphorylation, cell adhesion to the extracellular matrix, and expression of the inflammatory cytokines interferon-gamma and tumor necrosis factor-alpha. These immunotoxin effects were similar in magnitude to those induced by the unconjugated mAb. In contrast, immunotoxin-induced T cell proliferation was markedly less than that induced by the unconjugated mAb. Interestingly, the mitogenic molecules IL-2 and anti-CD28 mAb did not prevent immunotoxin-induced inhibition of cell proliferation.


CONCLUSIONS
The activation of T cells for protein phosphorylation, adhesion, and cytokine expression strongly suggests that the actions of FN18-CRM9 in vivo are not limited to the inhibition of protein synthesis.
Hamawy
M M
MM
Department of Surgery, University of Wisconsin, Madison 53792, USA.
Tsuchida
M
M
Manthei
E R
ER
Dong
Y
Y
Fechner
J E
JE
Knechtle
J S
JS
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017252:CD3 Complex / Q000276:immunology; D002448:Cell Adhesion / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism*; D005353:Fibronectins / Q000502:physiology; D000922:Immunotoxins / Q000494:pharmacology; D007371:Interferon-gamma / Q000235:genetics; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D016207:Cytokines; D005353:Fibronectins; D000922:Immunotoxins; D007376:Interleukin-2; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D011505:Protein-Tyrosine Kinases