Strong impact of CD4+ Foxp3+ regulatory T cells and limited effect of T cell-derived IL-10 on pathogen clearance during Plasmodium yoelii infection.

It is well established that CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) play a crucial role in the course of different infectious diseases. However, contradictory results have been published regarding to malaria infection. In this study, we report that specific ablation of Foxp3(+) Tregs in Plasmodium yoelii-infected DEREG-BALB/c mice leads to an increase in T cell activation accompanied by a significant decrease in parasitemia. To better understand how Foxp3(+) Tregs orchestrate this phenotype, we used microarrays to analyze CD4(+)CD25(+)Foxp3(+) Tregs and CD4(+)CD25(-)Foxp3(-) T cells in the course of P. yoelii infection. Using this approach we identified genes specifically upregulated in CD4(+)CD25(+)Foxp3(+) Tregs in the course of infection, such as G-protein-coupled receptor 83 and Socs2. This analysis also revealed that both CD4(+)CD25(+)Foxp3(+) Tregs and CD4(+)CD25(-)Foxp3(-) T cells upregulate CTLA-4, granzyme B, and, more strikingly, IL-10 during acute blood infection. Therefore, we aimed to define the function of T cell-derived IL-10 in this context by Cre/loxP-mediated selective conditional inactivation of the IL-10 gene in T cells. Unexpectedly, IL-10 ablation in T cells exerts only a minor effect on parasite clearance, even though CD8(+) T cells are more strongly activated, the production of IFN-γ and TNF-α by CD4(+)CD25(-) T cells is increased, and the suppressive activity of CD4(+)CD25(+) Tregs is reduced upon infection. In summary, these results suggest that CD4(+)Foxp3(+) Tregs modulate the course of P. yoelii infection in BALB/c mice. Moreover, CD4(+) T cell-derived IL-10 affects T effector function and Treg activity, but has only a limited direct effect on parasite clearance in this model.

Significance of intraepithelial lymphocytes in appendix.

The aim of this study was to investigate the importance of the increase in intraepithelial lymphocytes (IELs) in the mucosa of the appendix. One hundred and four retrospective appendectomy specimens were examined to evaluate the IELs. Intraepithelial lymphocytosis was identified in 11.5% (12 cases) of the specimens. Of these 12 cases, 6 cases with intraepithelial lymphocytosis were associated with parasitic infection. No increase in IELs was found in the 36 appendices that were removed in other primary operations. A wide range of immunologic stimuli can raise IELs in the gastrointestinal system. However, in appendectomies with clinical signs of acute appendicitis, an increase in IELs is more likely to be related to parasitic infection. This increase should be considered for the diagnosis of parasitic infections.

CD30 antigen expression in cutaneous inflammatory infiltrates of scabies: a dynamic immunophenotypic pattern that should be distinguished from lymphomatoid papulosis.

BACKGROUND: Expression of CD30 antigen is a distinct marker of lymphocyte activation that was originally described in the Reed-Sternberg cells of Hodgkin's disease. The observation of CD30+ cells has been considered a diagnostic feature of cutaneous CD30 lymphoid proliferations. However, CD30 expression has also been reported in some cutaneous benign inflammatory infiltrates. METHODS: Eleven skin biopsies from patients with scabies were double-blindly and retrospectively analysed. A panel of histopathological parameters and immunophenotypic expression of CD4, CD8, CD30 and S-100 antigens was studied. CD30 and S-100 antigens expression were related to clinical features. RESULTS: Large CD30+ cells were demonstrated in eight (8/11) biopsies, corresponding to patients with long-standing lesions (3 months or longer). However, no expression of the CD30 antigen was observed in all biopsy specimens (3/11) corresponding to early lesions (2 months or less). The presence of S-100 positive cells in the papillary dermis was an almost constant feature. CONCLUSIONS: CD30+ large cells seem to be a common feature in long-standing infiltrates of scabies. CD30 expression in scattered cells of a cutaneous lymphoid infiltrate cannot be assessed as a strong diagnostic argument of neoplastic cutaneous CD30+ lymphoid proliferation (lymphomatoid papulosis/cutaneous CD30+ lymphoma). Therefore, the possibility that large atypical CD30+ cells may be also present in several benign inflammatory diseases should be always considered.

Memory Th2 effector cells can develop in the absence of B7-1/B7-2, CD28 interactions, and effector Th cells after priming with an intestinal nematode parasite.

B7-1/B7-2 interactions are required for many Th2-cell mediated primary immune responses including the response that follows infection with the intestinal nematode parasite, Heligmosomoides polygyrus. However, few studies have examined the role of B7-1/B7-2/CD28 interactions in the development of a Th2 memory immune response. We examined the development of the memory Th2 response to H. polygyrus in BALB/c mice deficient in both B7-1 and B7-2 (B7-1/B7-2(-/-)) and in BALB/c mice deficient in CD28 (CD28(-/-)). Following primary inoculation with H. polygyrus, adult worms in the gut were cleared with an anti-helminthic drug and mice were subsequently challenge-inoculated with H. polygyrus larvae. The memory Th2 response is readily distinguished by its inhibitory effect on adult worm maturation, resulting in marked reductions in adult worm egg production that are not observed during the primary immune response. Following H. polygyrus challenge inoculation, comparable decreases in egg production and similar increases in mesenteric lymph node cell IL-4 production were observed in B7-1/B7-2(-/-) and B7-1/B7-2(+/+) mice. However, elevations in total serum IgG1 and IgE were reduced, while increases in serum Ag-specific IgG1 and IgE and germinal center formation were blocked in H. polygyrus-challenged B7-1/B7-2(-/-) mice. In contrast, in H. polygyrus-challenged CD28(-/-) mice, marked elevations in Ag-specific IgG1 and IgE and increased germinal center formation were observed. The results of these studies demonstrate that effector Th2 memory cells that produce IL-4 and mediate host defense can develop when B7-1/B7-2 interactions, and associated effector Th2 cell development, are blocked during priming. However, humoral immunity is impaired and differentially affected in B7-1/B7-2(-/-) mice and CD28(-/-) mice following H. polygyrus challenge.

[Acute infectious lymphocytosis associated to Giardia lamblia and Blastocystis hominis coinfection]. / Linfocitosis aguda infecciosa asociada acoinfección por Giardia lamblia y Blastocystis hominis.

Acute infectious lymphocytosis is characterized by marked peripheral blood lymphocytosis, often associated with a mild, nonspecific febrile illness. We present a 4-year-old girl with acute infectious lymphocytosis associated with Giardia lamblia and Blastocystis hominis coinfection. Analysis of peripheral lymphocyte markers showed overall proliferation of B and T cells with a reduction in the proportion of T cells, especially in the CD4T cell subpopulation. Hematologic values returned to normal after treatment with metronidazole.