Temperature requirements and kinetics of T cell signaling. Velocity of triggering correlates with functional effects of anti-CD3 mAb.
Antibody reactive with the CD3 complex on the surface of T lymphocytes can either: inhibit CTL lysis of target cells expressing Ag; or redirect CTL to lyse target cells expressing FcR in the absence of Ag expression. To investigate these phenomena we examined the effect of anti-CD3 mAb on two indicators of CTL activation, the release of esterase and target cell lysis. Esterase release by long term allo-reactive human CTL in response to target cells (JY or HLA transfected K562 cells) was found to be Ag specific and correlate with target cell lysis. Addition of anti-CD3 to either JY targets or K562 cells expressing FcR resulted in a high level of esterase release. Triggering of esterase release was found with both soluble intact and Fab fragment of anti-CD3 in the absence of cells expressing measurable FcR. This apparent FcR-independent triggering of esterase release occurred at 37 degrees C but not at 24 degrees C. In contrast esterase activity was released from CTL at both 24 and 37 degrees C in response to intact target cells, JY or K562 cells plus intact anti-CD3 mAb. Addition of anti-CD3 mAb, at a level capable of blocking target cell lysis by greater than 50%, resulted in an initial velocity of esterase release almost twice that found in response to JY target cells. With a low level of anti-CD3 mAb, able to block JY lysis by approximately 10%, the initial rate of esterase release was much slower than that found in response to target cells. In contrast when FcR+ cells, K562, were added along with a low level of anti-CD3 the initial velocity of esterase release was about twofold more than the velocity of esterase release triggered by soluble anti-CD3 alone. These results indicate that soluble antibody can trigger long term active CTL and the velocity of this triggering correlates with anti-CD3-mediated inhibition as well as redirected lysis.
Abdi
K
K
Department of Pathology, Harvard Medical School, Boston, MA 02115.
Reed
M L
ML
Mentzer
S J
SJ
Herrmann
S H
SH
D000911:Antibodies, Monoclonal / Q000502:physiology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D017252:CD3 Complex; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D000939:Epitopes / Q000032:analysis; D004950:Esterases / Q000378:metabolism; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000502:physiology; D007700:Kinetics; D008213:Lymphocyte Activation; D016853:Muromonab-CD3; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D011961:Receptors, Fc / Q000502:physiology; D013602:T-Lymphocytes, Cytotoxic / Q000201:enzymology / Q000276:immunology*; D013696:Temperature
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D000939:Epitopes; D007140:Immunoglobulin Fab Fragments; D016853:Muromonab-CD3; D011948:Receptors, Antigen, T-Cell; D011961:Receptors, Fc; D004950:Esterases; C022635:serine esterase