Roberta Biagiotti

Purified protein derivative of Mycobacterium tuberculosis and excretory-secretory antigen(s) of Toxocara canis expand in vitro human T cells with stable and opposite (type 1 T helper or type 2 T helper) profile of cytokine production.

A large series of T cell clones (TCC) specific for purified protein derivative (PPD) of Mycobacterium tuberculosis (total 60) or Toxocara canis excretory/secretory (TES) antigen (total 69) were established from the peripheral blood of two healthy individuals and analyzed for their profile of cytokine production in response to stimulation with either the specific antigen or the polyclonal activator phorbol myristate acetate plus anti-CD3 antibody. Under both these experimental conditions, the great majority of PPD-specific TCC secreted IL-2 and IFN-gamma but not, or limited amounts of, IL-4 and IL-5. In contrast, most TES-specific TCC secreted IL-4 and IL-5 but not, or limited amounts of, IL-2 and IFN-gamma. PPD-specific TCC that failed to secrete IL-4 and IL-5, and TES-specific TCC that failed to secrete IL-2 and IFN-gamma, were found to lack transcripts for IL-4 and IL-5, or for IL-2 and IFN-gamma, respectively. During the course of the study, over a 6-mo period, the functional phenotype of both TES- and PPD-specific TCC was repeatedly assessed and remained constant. These data demonstrate that T cells with stable Th1 or Th2 functional pattern exist not only in mice but also in humans and suggest that in the course of natural immunization certain infectious agents preferentially expand T cell subsets with stable and definite profile of cytokine production.

Expression and release of LAG-3-encoded protein by human CD4+ T cells are associated with IFN-gamma production .

The lymphocyte activation gene (LAG) ‐3 is a member of the immunoglobulin superfamily that is selectively transcribed in human activated T and NK cells. In this work, the possibility that LAG‐3 expression by human CD4+ T cells was preferentially related to one or another phenotype of cytokine secretion was investigated. Surface LAG‐3 expression correlated with IFN‐γ, but not IL‐4, production in antigen‐stimulated T cells and it was up‐ regulated by IL‐12. Most activated CD4+ T cell clones with established Thl or Th0 profiles of cytokine secretion expressed LAG‐3 on their surface, whereas the great majority of Th2 clones showed 1 neither surface LAG‐3 nor LAG‐3 mRNA expression. After activation, the majority of CD4+ T cell clones also released soluble LAG‐3‐related peptides, and such a release correlated positively with the production of IFN‐γ and inversely with the production of IL‐4. Thus, LAG‐3 expression by activated CD4+ human T cells appear to be preferentially associated with the differentiation/activation pathway leading to the production of IFN‐γ.—Annunziato, F., Manetti R., Tomase vie, L., Guidizi, M.‐G., Biagiotti, R., Giannö, V., Germano, P., Mavilia, C., Maggi, E., Romagnani, S. Expression and release of LAG‐3‐encoded protein by human CD4+ T cells are associated with IFN‐γ production. FASEB J. 10, 769‐775 (1996)

Human TH1 and TH2 Subsets

Human CD4+ T cell clones secreting different patterns of cytokines similar to TH1 and TH2 cells described in mice have been demonstrated. These human TH1 and TH2 clones are produced in response to different antigens and exhibit distinct functional properties. TH1 clones are produced in response to intracellular bacteria and viruses, do not provide help for IgE production and possess cytolytic potential, whereas TH2 clones are produced in response to allergens and helminth components, provide optimal help for IgM, IgG, IgA and IgE synthesis, and lack cytolytic potential. The cytokine profile of ‘natural’ immunity evoked by intracellular parasites and viruses through the activation of macrophages and NK cells probably determines the phenotype of the subsequent specific immune (TH1) response. TH1 cells are not only involved in the protection against intracellular parasites but also play a role in the genesis of some organ-specific autoimmune diseases, such as Hashimoto’s thyroiditis. In contrast, TH2 cells are responsible for the initiation of the allergic cascade.

Activation of HIV expression by CD30 triggering in CD4+ T cells from HIV-infected individuals

CD30 is a member of the tumor necrosis factor receptor superfamily, preferentially expressed by T cells producing type 2 helper (Th2) cytokines, whose ligand (CD30L) has been identified on B cells, activated macrophages, and a subset of activated T cells. We show here that cross-linking CD30 with an agonistic CD30-specific monoclonal antibody, as well as with CD30L+ CD8+ T cell clones or CD30L+ B cells, enhanced HIV replication in CD4+ T cells from HIV-infected individuals, and such a potentiating effect was inhibited by anti-CD30L antibody. The anti-CD30L antibody also exerted a suppressive effect on spontaneous HIV replication occurring in lymph node cells from an HIV-sero-positive patient, showing CD30L expression by both B and CD8+ T lymphocytes. Thus, CD30 triggering by CD30L-expressing cells may plan an important role in the activation of HIV expression from latently infected CD4+ T cells.

Altered proportion of T mu-and T gamma-cell subpopulations in patients with Hodgkin's disease.

The ability of peripheral blood lymphocytes from patients with Hodgkins disease (HD) to form rosettes with ox red blood cells (ORBC) sensitized by anti‐ORBC purified rabbit IgM and IgG was investigated. The mean percentage of cells capable of forming rosettes with ORBC coated with IgM (EAIgM‐RFC) in the peripheral blood of either untreated or X‐ray‐treated patients with HD was significantly lower than that of normal individuals. In the same groups of patients with HD the mean percentage of T lymphocytes equipped with receptor for IgG (Tγ lymphocytes), evaluated by a mixed fluorescent rosette assay, was significantly higher than in normal controls. These data suggest that the altered proportion between Tμ‐ and Tγ‐cell subpopulations in patients with HD probably represents a disease‐related phenomenon.

Frequency of a mutated CCR-5 allele (delta32) among Italian healthy donors and individuals at risk of parenteral HIV infection.

The aim of this study was to assess the frequency of a truncated allele of the CCR-5 gene (delta32) in Italy, and address its possible role in parenteral HIV transmission, as well as its influence in HIV-associated disease progression. In 371 unrelated seronegative healthy blood donors the delta32 allele frequency was 0.047; this figure was significantly different from those reported in northern America and northern Europe populations. However, delta32 allele frequency in healthy individuals did not differ significantly from that found in 54 seronegative drug users (0.065), 98 seronegative hemophiliacs (0.051), and 81 seropositive hemophiliacs (0.049). Although in seropositive hemophiliacs the wt/delta32 heterozygous genotype was associated with a trend to a slower decline in CD4+ cell counts, its presence did not seem to influence disease progression, as comparable delta32 allele frequency frequencies were found among progressing (0.042) and nonprogressing (0.111) patients. These data do not seem to support a protective role of the delta32 allele in preventing HIV infection through the parenteral route, or in influencing the natural history of the disease in this particular risk category, although the delta32 heterozygous state was associated with lower plasma viremia levels. On the other hand, the finding of non-syncytium-inducing HIV strains in the majority of delta32 heterozygous seropositive patients suggests that its presence could not be a major factor in driving a switch toward more cytopathic, T-tropic HIV strains through selective pressure in coreceptor usage.

Type 1 T Helper Cells Specific for Candida albicans Antigens in Peripheral Blood and Vaginal Mucosa of Women with Recurrent Vaginal Candidiasis

The cytokine profile of circulating and vaginal T cells specific for immunodominant mannoprotein antigens of Candida albicans was analyzed in patients with recurrent vaginal candidiasis (RVC). Peripheral blood mononuclear cells (PBMC) from patients with RVC proliferated more than those from healthy subjects and expressed higher type 1:type 2 T helper cell cytokine ratios in response to C. albicans stimulation. A higher number of C. albicans-specific T cells was generated in PBMC from patients with RVC than in PBMC from healthy donors. C. albicans-specific T cell clones from patients with RVC produced higher levels of interferon (IFN)-gamma and lower levels of interleukin (IL)-4 than clones from control women. More important, a higher proportion of C. albicans-specific T cell clones was generated from lesional mucosa of patients with RVC than from normal mucosa, all of which produced IFN-gamma but not IL-4. These findings provide direct evidence that RVC is characterized by a highly polarized local and circulating type 1 T helper cell-like response against C. albicans antigens.

Hyperproduction of IgE and T-cell dysfunction in Hodgkin's disease.

Serum IgE levels were evaluated in 119 untreated and 112 treated patients with Hodgkins disease (HD). 38 of the nonatopic untreated patients showed significantly increased (> 300 IU/ml) IgE concentrations. No relationship could be found between increased IgE levels and depressed lymphocyte response to phytohemagglutinin (PHA) or the imbalance of TM and TG lymphocyte subsets. On the other hand, the mean level of suppressor activity elicitable from cells of untreated HD patients by concanavalin A preincubation did not differ significantly from that of healthy control subjects. In contrast, in treated patients, where there was a significant reduction in the number of circulating T lymphocytes, a further depression of the lymphocyte response to PHA, a more marked disproportion of TM and TG cell subsets and a noticeable fall in IgE concentration was found. These data suggest that increased IgE concentrations seen in untreated patients with HD are unrelated to the T-cell defects. They also suggest that hyperproduction of IgE is probably not invariably a consequence of a suppressor cell deficiency.

Anti-Ia reactivity in sera of untreated patients with active Hodgkin's disease.

The effect of sera from eight patients with Hodgkins disease on the autologous and allogeneic mixed lymphocyte response of normal individuals was examined. Sera from three patients with active disease caused marked inhibition of both autologous and allogeneic mixed lymphocyte reaction without inducing significant reduction of the phytohemagglutinin-induced proliferative response. The inhibitory activity of Hodgkins disease sera on the autologous mixed lymphocyte reaction was removed by adsorption with non-T, but not T, lymphocytes and it was correlated with the ability of such sera to block the binding of monoclonal anti-Ia antibody to Ia-positive target cells. Anti-Ia antibodies were detected in the same sera by double antibody radioimmunoassay and analysis on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, using 125I-labeled, partially purified, Ia antigens from two different human B-cell lines. This anti-Ia reactivity was strongly reduced or absent in sera taken from the same patients at the completion of multidrug chemotherapy.

Role for CD30 in HIV expression.

CD30 is a member of the tumor necrosis factor (TNF)-receptor superfamily, whose ligand (CD30L) has been identified on B cells, activated macrophages and a subset of activated T cells. We show here that infection in vitro with human immunodeficiency virus (HIV) of CD4+ T-cell clones generated from HIV-seronegative individuals can enhance the expression of CD30, which often preceeds and is associated with the death of clonal T cells. Furthermore, cross-linking CD30 with an agonistic CD30-specific monoclonal antibody potentiated HIV replication induced by an insolubilized anti-CD3 antibody in T-cell lines generated from HIV-infected individuals. More importantly, paraformaldehyde-fixed CD8+ T-cell clones expressing CD30L enhanced HIV replication in anti-CD3-stimulated allogeneic or autologous HIV-infected CD4+ T-cell lines and such a potentiating effect was inhibited by an anti-CD30L antibody. The anti-CD30L antibody also exerted a suppressive effect on the spontaneous HIV replication occurring in lymph node cells, freshly derived from an HIV-seropositive patient showing CD30 expression in B cells and in a proportion of CD8+ T lymphocytes. Thus, CD30 triggering may play an important role in both HIV replication and the death of HIV-infected CD4+ T cells.