Cytokines Involved in the Pathophysiology of IgE Response

Recent data in both mouse and human systems have clearly indicated that IL-4 plays an essential role in the induction of IgE response, whereas IFN-γ exerts an opposite effect on this phenomenon. However, IL-4 alone is unable to induce IgE synthesis. A prior membrane contact signal delivered by activated T cells is required by B cells to synthesize IgE in response to IL-4. A cognate interaction between B and T cells producing IL-4 (but not IFN-γ) is optimal for induction of IgE synthesis. However, when such IL-4 producing T cells are activated, they may provide B cells with a membrane signal, through a non-cognate interaction, which also results in induction of IgE synthesis. Other cytokines, such as IL-2 and IL-6, play an auxiliary role in IL-4 dependent IgE production.

Analyses at the clonal level of the profile of cytokine production by helper T cells have shown that imbalances between IL-4 and IFN-γ producing T cells can be detected in patients with hyperproduction of IgE. In children with hyper-IgE syndrome a strong reduction of circulating T cells able to produce IFN-γ (and TNF-α) was found, whereas both, reduction of IFN-γ-producing and increase of IL-4 producing T cells were found in patients with parasitic infestation. In allergic inflammatory infiltrates, such as those found in vernal conjuctivitis, helper T cells able to produce IL-4 and to induce IgE synthesis accounted for the large majority of infiltrating T cells. It is reasonable to suggest that systemic or microenvironmental alterations of the balance between IL-4- and IFN-γ-producing T cells may be involved, at least in part, in the pathophysiology of the increased igE response occurring in a number of human diseases.

Cytokines and Thyroid Autoimmunity

Cytokines may play important roles in the development and perpetuation of autoimmunity. In this paper are briefly reviewed selected data on the relationship between cytokines and thyroid autoimmune diseases (AITD), which represent a typical example of organ-specific autoimmune endocrinopathy. The availability of high efficiency T-cell cloning techniques recently allowed the phenotipic and functional characterization of T lymphocytes derived from thyroid infiltrates of patients with Graves' disease and Hashimoto's thyroiditis. A high prevalence of T cell clones with cytolytic potential and displaying increased γ-interferon production was observed in both diseases; in contrast, high tumor necrosis factor-α secretion was a peculiar characteristic of T-cell clones derived only from Hashimoto's infiltrates. The production of IL-4 by CD4 + T cell clones from AITD infiltrates was remarkably low, suggesting a quite homogeneous populations of Thl-type «inflammatory» T cells. This pattern of cytokine production by thyroid infiltrates may be important not only in triggering and/or maintaining thyroid autoimmune reaction, but could also modulate the expression of AITD by exerting direct functional effects on thyroid epithelial cells, as suggested by recent in vitro studies.

Chondromalacia of the patella. Natural progression

A total of 42 cases of patellar pain in subjects aged an average of 17.2 years submitted to arthroscopy are analyzed. Femoropatellar balance, where indicated, led to resolution of disorders with full resumption of sports activity. In the remaining cases chondromalacia showed the features of an affection with a spontaneously favorable course, confirming the common orientation towards conservative treatment. Arthroscopy is effective for a correct classification of cartilaginous lesions, and it is a good instrument to use when attempting to achieve recovery of patellofemoral joint when disorders are caused by a lack of equilibrium.