Intestinal Strongyloidiasis : Recognition, Management, and Determinants of Outcome

Several specific conclusions can be drawn from these studies: 1. IL-4 is required for the generation of both primary polyclonal and secondary antigen-specific IgE responses in vivo. 2. IL-4 is required to maintain established, ongoing, antigen-specific and polyclonal IgE responses. 3. Most, but not all, polyclonal IgE production during a secondary immune response is IL-4-dependent. Memory B cells that have already switched to IgE at the DNA level may no longer require stimulation with IL-4 to be induced to secrete IgE. 4. The generation of a secondary IgE response is not dependent upon the presence of IL-4 during primary immunization. However, if IL-4 is not present during primary immunization, it is required during secondary immunization for the generation of an IgE response. 5. IL-4 does not appear to be required for the generation of in vivo IgG1 responses, and in at least some instances, does not contribute significantly to the generation of IgG1 responses in vivo. 6. A late-acting form of T-cell help other than IL-4 appears to be required for the generation of an IgE, but not an IgG1 response. 7. An antibody that inhibits IL-4 binding to IL-4 receptors affects Ig isotype selection in the same way as an antibody that neutralizes IL-4. 8. IFN-gamma can act in both spontaneous and induced immune responses to suppress IgE production. 9. IFN-gamma can also suppress IgG1 production and stimulate IgG2a production. However, IFN-gamma appears to suppress polyclonal IgG1 responses more than antigen-specific IgG1 responses, and it enhances, but is not required for, the generation of IgG2a responses. 10. IFN-alpha appears to resemble IFN-gamma in its ability to inhibit IgE and enhance IgG2a responses in GaM delta-injected mice, but it requires the presence of IFN-gamma to suppress IgG1 production in these mice. 11. Both IFN-alpha and IFN-gamma appear to be able to decrease IgE production in some human patients. 12. There is no direct evidence that IL-5 contributes to the generation of in vivo antibody responses. Two general conclusions may also be drawn.(ABSTRACT TRUNCATED AT 400 WORDS)

In Jamaican children infective dermatitis is a chronic eczema associated with refractory nonvirulent Staphylococcus aureus or beta-haemolytic streptococcus infection of the skin and nasal vestibule. 14 children between the ages of 2 and 17 years with typical infective dermatitis, attending the dermatology clinic at the University Hospital of the West Indies in Jamaica, were tested for antibody to human T-lymphotropic virus type 1 (HTLV-1). All were seropositive, whereas 11 children of similar age with atopic eczema were all negative. In 2 of 2 cases of infective dermatitis, the biological mother was HTLV-1 seropositive. None of the 14 patients showed signs of adult T-cell leukaemia/lymphoma, though experience with previous cases of infective dermatitis indicates the possibility of such progression.

Parasitic protozoa and helminths are a diverse group of organisms which together form a major cause of infectious disease in humans and livestock. Studies in animal models have revealed that T lymphocytes and the cytokines they produce play a crucial role in determining the outcome of parasitic infection in terms of both protective immunity and immunopathology. Of particular interest is recent evidence that different parasitic infections in the context of different host genetic background can trigger polarized CD4+ T cell subset responses. The set of cytokines produced by these different T helper responses, in turn, can have opposing effects on the parasite, resulting in either control of infection or promotion of disease. Moreover, cytokines produced by one CD4+ subset can block either the production and/or activity of the cytokines produced by the other subset. The establishment of this state of cross-regulation may be important for parasite survival. CD8+ T cells also appear to play a dual effector/regulatory role in parasite immunity and immunopathology, although the mechanisms underlying their induction and function are less well understood. CD(8+)-mediated cytolytic killing functions have now been demonstrated against a number of different intracellular protozoa, although IFN-gamma produced by the same effector cells may also be critical in host community. In addition to providing highly relevant models for studying the selection and immunobiologic function of T-cell subsets, research on T lymphocyte-parasite interactions is crucial for the design of effective vaccines and immunotherapies and thus has broad practical as well as theoretical ramifications.