Conference Scene: T-cell subset phenotype and function.

Organized by Euroscicon, this meeting focused on the complex and fast-paced research field of T-cell subset phenotype and function. During the past 20 years, this field has moved on from the simple Th1-Th2 paradigm to the discovery of a range of T-cell subsets, including Tregs and Th17 cells. The meeting brought together a variety of researchers currently exploring this field, to give insight into what we know, what we need to know and the potential implications of this research in the medical setting.

Immunopathology of parasitic diseases: a conceptual approach.

These studies would indicate tremendous variations in the clinical manifestations of parasitic disease, resulting from characteristics of the parasite, the host, and their interaction. They further suggest that the conceptual mechanistic model described in the introduction is highly applicable. Previous evidence to substantiate the validity of such a model in schistosomiasis, a variety of protozoan diseases, and leprosy has already been presented (Phillips and Fox, 1982). This report would appear to lend additional credence to the postulates and suggests that upon scrutiny, the model represents a reasonable explanation for a wide variety of clinical manifestations of a parasitic disease. In addition, it may provide a working hypothesis for the interpretation of the immunopathology found in other diseases such as filariasis. Figure 3 compares and contrasts schistosomiasis and filariasis within the context of this hypothesis. Immunopathology results from the relative balance of host-parasite immunogenic factors and modulatory specific and nonspecific factors. The resultant immunopathology results from a number of immunologic mechanisms, but for the sake of comparison can be placed in certain analogous groups. Clearly, although a number of experimental questions still exist, vis-à-vis these analogies, it would appear that they are reasonable comparisons. It is hoped that such a conceptual approach might provide a useful framework for an understanding of the spectrum of immunopathology resulting from parasitic disease. These concepts might possibly lead to the eventual control of immunopathology.

Immunologic aspects of leprosy with special reference to the study of immunoglobulin E.

The serum levels of IgG, IgM, IgD and IgE have been determined in normal subjects, individuals suffering from ascariasis and filariasis, and in leprosy patients. Allergic and parasitic diseases were excluded in these normal subjects and in leprosy patients before they were taken for the study of their serum IgE. The circulating IgG was significantly raised in both tuberculoid and lepromatous forms of leprosy and also in filariasis; IgM was significantly elevated in only the lepromatous form of leprosy, ascariasis as well as in filariasis; while IgA was exclusively raised in both forms of leprosy. IgD was detected in the sera of more subjects with ascariasis and filariasis than in normal individuals and leprosy patients. The mean level of serum IgE in 35 normal Indian subjects was 1,025 I.U. per ml, 9 of them (25%) having serum IgE concentrations above 700 I.U. per ml. The highest mean level of serum IgE was found in ascariasis (7,328 I.U. per ml), followed by leprosy (5,180 I.U. per ml), and filariasis (4,244 I.U. per ml). Furthermore, no significant difference between the mean serum IgE levels of tuberculoid and lepromatous leprosy patients was observed. Although the rise of serum IgE level in these parasitic diseases, as well as in leprosy, was spectacular, the augmented synthesis of this unique class of immunoglobulins was not invariably present in all patients. The results have been discussed on the basis of recent ideas on immunoglobulin synthesis.