Pinpointing when T cell costimulatory receptor CTLA-4 is Engaged!!!! Melanoma..Jim Breitfeller

Pinpointing when T cell costimulatory receptor CTLA-4 Is Engaged. In my therapy, I am trying to follow what had transpired and to try to back the findings up with scientific facts.

So, after the inoculation of the 15mg/Kg of Tremelimumab (from Pfizer) IgG2 what happened? Based on scientific theory the Monoclonal antibody blocks the CTLA-4 receptor causing the T-cell to stay active. So If my body’s chemistry is right, when and how do we know if the CTLA-4 blockage is engaged?

Dr. James Allison and colleagues in the late 1990’s did some studies with mice. In the mouse model, the anti-CTLA-4 blockage caused an autoimmune response which was diabetes in the mice. Before I go any further, I must make a note of caution. That is not all immune responses in mice models crossover to the human model, but the models are usually a good predictor. So with that said, In the research paper “Pinpointing when the T-cell costimulatory receptor CTLA-4 must be engaged to dampen diabetogenic T-cells”, it took about 12 days to see a response to the Anti-CTLA-4 mAb.

Source: http://www.pnas.org/content/97/22/12204.full

Pinpointing when the T-cell costimulatory receptor CTLA-4 must be engaged to dampen diabetogenic T-cells



Well in my therapy, an inflammatory response was noted on day 15. This suggests that the costimulatory receptor was fully engage to cause a inflammatory response, The “Danger Signal”

“Three major events must occur to induce CD8+ T cell–mediated, tumor-protective immunity against syngeneic melanoma. First, the T-cell receptor must be triggered by a (or multiple) self antigen–derived peptide MHC class I complex (7–13). Therefore, this event depends entirely on appropriate antigen presentation, which is most efficiently provided by mature dendritic cells (14). Peripherally tolerant or “ignorant” self-reactive T-cell clones, once properly activated, may serve as tumor-specific effector T cells (15, 16). Second, simultaneously with T-cell receptor triggering, a distinct second costimulatory signal must be delivered, mediated by IL-2, B7-1, or B7-2, which engage IL-2 receptors and CD28 on the surface of the T cell, respectively (17). A source of these cofactors for effective CD8+ T-cell stimulation can be provided by CD4+ T cells that release critical amounts of IL-2, or by mature dendritic cells that display an increased level of B7-1/B7-2 costimulatory molecules on their cell surfaces. Third, inflammatory cytokines, including IL-1, IL-6, IL-12, and IFN-γ provide a third signal that acts directly on T cells (18), referred to as the “danger signal” (19, 20). This signal was found to optimally activate TH1 differentiation and lead to clonal expansion of T cells (18).”

Source: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=300854