Immune responses polarization

Finally, besides conventional liposomes that are made from natural (e.g., egg yolk and soybean) or synthetic phospholipids, novel liposomes called archaeosomes that are prepared from the polar ether lipids extracted from various archaeobacteria proved also interesting for the design of vaccines as peptide antigen carriers (71) and as powerful self-adjuvanting vaccine delivery vesicles that promote both humoral and cell-mediated immunity (72). Related to this, one can mention that pseudopeptides, which are less prone to proteolysis when conjugated to liposomes, were also competent in triggering a humoral immune response (73). 

The innate and the adaptive arms of the immune systems of higher organisms are bridged by a complex set of cellular and molecular mediators. The immunomodulatory activities of host defense peptides, such as the direct chemotactic activity, cytokine and chemokine induction, and the stimulation of differentiation and activation of effector cells, may contribute to this process. Host defense peptides may also influence the polarization of adaptive immune response, for example, through their effects on cytokine production. ... 

Fig. 9.2. Simplified schema of the development of T helper type 1 (Th1) and 2 (Th2) cells under the influence of interleukin (IL)-12 and IL-4, respectively, and how these two polarized T cell phenotypes produce cross-inhibitory cytokine profiles and promote different aspects of the host immune response (IFNy, interferon-gamma TNFa, tumour necrosis factor alpha Thr, T helper regulatory cell Th3, T helper type 3 cell).

The cellular sources for the polarized immune response in the CNS are astrocytes and microglia cells. Microglial cells, deriving fi omperipheral macrophages, secrete preferably type-1 cytokines such as IL-12, while astrocytes inhibit the production of IL-12 andICAM-1 and secrete the type-2 cytokine IL-10 (Xiao and Link, 1999 Alois etal., 1997). Therefore, the type-l/type-2 imbalance in the CNS seems to be represented... 

The pattern of proinflammatory cytokines produced has implicadons for the character of the adapdve immune response, which will occur if the host is exposed to a foreign andgen. A T-helper type 1 (Thl) cytokine profile polarizes the immune response tov ards a cellular immune response, whereas a T-helper type 2 (Th2) profile favors andbody responses (Mos-mann and Coffman, 1987). IFN-y is a marker of a Thl response, and IL-4 is indicadve of a Th2 response. There is evidence that morphine given in vivo biases the immune response tovm d a Th2 response (Roy et al., 2004). The consequences of this apparent shift toward Th2-type immunity are not clear, since other studies show that andbody producdon is suppressed in animals treated similarly with morphine (Bus-si ere et al., 1993). These results will be discussed in greater detail below. 

A -THC, like morphine, has been shown to suppress in vitro antibody formation by mouse spleen cells (Kaminski et al., 1992 Kaminski et al., 1994). Interestingly, A -THC is reported to increase IgGl responses to Legionella pneumophila in drug-treated animals, presumably by polarizing the immune response towards a Th2 phenotype (see below under T cell responses) (Newton et al., 1994). 

Thl/Tli2 subclasses of T helper cells that are distinguished by their cytokine profiles. Thl cells are characterized by production of IFN-g. Thl cells are characterized by production of IL-4. Th2 cells polarize the immune response towards cellular immunity and Th2 cells polarize towards antibody formation. 

---