Cd4 Supply Chain

Human immune responses are controlled by a myriad of cells and cell surface receptors. CD4 is a cell surface receptor found on T cells which both recruits and regulates immune response. When CD4 is knocked out, different processes and functions are found. IL-2 secretion is linked to CD4 and MHC II, linking CD4 and MHC II in immune responses. While important in T cell development, CD4 is not required to ensure proper haemopoiesis, and CD8 T cells can differentiate with CD4 present. CD4 is also integral in antibody response against antigens, as it recruits B cells. In Graft-versus-host disease, CD4 plays important roles in the development of the disease post-transplant. Donor effector CD4 cells are one of the key factors in initiating the immune …show more content…
B cells and T cells are the central cell types with adaptive immunity, working together to conduct responses. B cells produce antibodies, while the T cells are differentiated into cytotoxic T cells and helper T cells. Helper T cells express CD4 on their cell surface, binding antigens and associating with MHC class II. T cells initially express CD4 and CD8 before maturation in the thymus, where positive selection enhances production of either CD4 or CD8 (Geginat, 1). Upon maturation, the CD4 T cells are considered naïve, until the cells are induced in an immune response. There are five major types of induced helper T cells, each with a different functionality and CD4-associated cytokine. T helper 1 cells produce IFN-, stemming from exposure to IL-12 (Nakayamada, 1). Differentiation of the other helper T cell types occurs in the presence of IL-4 (Geginat, 1). T helper 2 cells produce IL-4 and are able to trigger an IgE response from B cells (Nakayamada, 1). T helper 17 cells express IL-17 (and IL-22 and IL-26 in lower quantities), while type 1 regulatory-like T cells produce TGF- (Geginat, 2). The final subset of helper T cells known today are follicular helper T cells which produce IL-21 (Nakayamada, 2). There is limited plasticity between the subsets, where Th-1 cells can begin secreting IL-10, and differentiate to TREG cells (Geginat, 2). Each subset of helper T cells aids in different immunologic …show more content…
IL-2 secretion shows that CD4 associates with MHC II but not MHC I. As IL-2 associates with CD4, if the association was exclusive, the IL-2 secretions would be knocked out in the homozygous mice. The IL-2 associations were observed in order to determine if IL-2 binds preferentially to MHC I or MHC II, to determine if IL-2 is secreted by only CD4 or also by CD8. In order to determine the responsivity of IL-2, spleen cells which expressed either MHC I, MHC II, or both were observed. The cells were homozygous for CD4 knockout, while CD8 was expressed normally. In the spleen cells, the IL-2 levels differed between homozygous and heterozygous mice: for MHC II response, the heterozygous mice secreted higher IL-2, while homozygous mice secreted higher IL-2 for MHC I response. The secretion levels were monitored and compared against each other. The results show the association of IL-2 with CD4 and MHC, not one or the other. In the MHC II response, the heterozygous mice express CD4 which heightens the IL-2 levels, allowing for greater association with the MHC classes. The IL-2 secretion levels are roughly 7 units for the MHC II only cells, while the MHC I cells show 2.5 units and both show less than 2 units. These results help to confirm the associations of CD4 and CD8 with the respective MHC classes, II and I. As CD4 associates with MHC II, the secretion levels would

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