Rat-specific IgG and IgG4 antibodies associated with inhibition of IgE-allergen complex binding in laboratory animal workers.

OBJECTIVES: The relationship between exposure to rodent allergens and laboratory animal allergy is complex; at highest allergen exposures there is an attenuation of sensitisation and symptoms which are associated with increased levels of rat-specific immunoglobulin (Ig)G and IgG4 antibodies. We set out to examine whether the increased levels of rat-specific IgG and IgG4 antibodies that we have previously observed at high allergen exposure in our cohort of laboratory animal workers play a functional role through blockage of the binding of IgE-allergen complex binding to CD23 receptors on B cells. METHODS: Cross-sectional survey of laboratory animal workers (n=776) in six UK pharmaceutical companies were surveyed. IgE-allergen complex binding to B cells was measured in 703 (97.9%) eligible employees; their exposure was categorised by either job group or number of rats handled daily. RESULTS: We observed a significant decrease in IgE-allergen complex binding to B cells with increasing quartiles of both rat-specific IgG and IgG4 antibodies (p<0.001). IgE-allergen complex binding to B cells was lower in workers with high allergen exposure, and significantly so (p=0.033) in the subgroup with highest exposures but no work-related chest symptoms. CONCLUSIONS: These findings demonstrate a functional role for rat-specific IgG/G4 antibodies in laboratory animal workers, similar to that observed in patients treated with high dose immunotherapy who become clinically tolerant, suggesting a potential explanation for the attenuation of risk at highest allergen exposures.

Functional rather than immunoreactive levels of IgG4 correlate closely with clinical response to grass pollen immunotherapy.

BACKGROUND: Induction of allergen-specific IgG(4) antibodies is the most consistent immunological finding in immunotherapy trials. However, quantitative assessments of IgG(4) antibodies have not proven beneficial in evaluating clinical changes during or after immunotherapy. In the current study, we investigated the relationship between clinical outcome and allergen-specific IgG(4) titres or functional antibody responses following immunotherapy. We hypothesized that functional assays of serum IgG-associated inhibitory activity such as inhibition of IgE-allergen interactions (IgE-blocking factor) and inhibition of CD23-dependent IgE-facilitated allergen binding (IgE-FAB) correlate more closely with clinical outcome and may be biomarkers of clinical response. METHODS: In an 8-month dose-response randomized double-blind placebo-controlled study, 221 polysensitized subjects with severe seasonal rhinitis received Alutard SQ, Phleum pratense 100,000 SQ-U, 10,000 SQ-U or placebo injections. Serum specimens were collected before treatment, after up-dosing, during the peak season and at the end of the study. Allergen-specific IgG(4) titres and IgG-associated inhibitory activity were evaluated. RESULTS: A time- and dose-dependent increase in serum inhibitory activity for both the IgE-blocking factor and IgE-FAB was observed, which paralleled increases in grass pollen-specific IgG(4) antibodies. A modest but significant inverse relationship was demonstrated between postimmunotherapy serum inhibitory activity and combined symptom-rescue medication scores (IgE-FAB: r = -0.25, P = 0.0002; IgE-blocking factor: r = -0.28, P < 0.0001), whereas this was not observed for immunoreactive IgG(4) levels (r = -0.11, P = 0.12). CONCLUSIONS: Functional assays of inhibitory IgG(4) and IgE-blocking factor may be more useful surrogates of clinical response than IgG(4). Whether these antibody effects may serve as predictive biomarkers of clinical efficacy in individual patients requires further investigation.

Time course of serum inhibitory activity for facilitated allergen-IgE binding during bee venom immunotherapy in children.

BACKGROUND: Immunotherapy for bee venom allergy is effective and provides long-term protection. Venom-specific IgG4 levels are increased but with no correlation with clinical improvement. Following grass pollen immunotherapy, elevation of antigen-specific IgG4 is accompanied by increases in IgG-dependent serum inhibitory activity for IgE-facilitated binding of allergen-IgE complexes to B cells. As this 'functional' assay of inhibitory antibodies may be more predictive of clinical efficacy, we investigated the time course of serum inhibitory activity for IgE-facilitated antigen binding during venom immunotherapy (VIT) in children and following 2 years of VIT withdrawal. METHODS: Ten bee venom-allergic children (mean age: 9.3 years; m/f, 7/3) with moderate to severe allergic reactions to bee stings received VIT. A separate group of seven children (mean age: 14 years; m/f, 5/2) were investigated 2 years after VIT withdrawal. Ten age- and gender-matched children served as non-allergic controls. Allergen-specific serum IgG4 and IgE levels were measured by ELISA at baseline, after 2 years of VIT and 2 years after VIT withdrawal. Serum inhibitory activity was assessed using the facilitated-allergen binding (FAB) assay. RESULTS: Sera obtained during VIT significantly inhibited allergen-IgE binding to B-cells (pre-treatment=104+/-23%; 2 years=46+/-15%; P<0.001) when compared with sera obtained after treatment withdrawal and sera from normal controls. In parallel to FAB inhibition during VIT, significantly higher IgG4 levels were noted after immunotherapy (pre-treatment=8.6+/-2.3 AU; 2 years=26.7+/-3.5 AU; P<0.001) compared with those observed after withdrawal and in the controls. In contrast, progressively lower IgE concentrations were observed compared with pre-treatment (44+/-7 AU) in sera obtained after 2 years of VIT (25+/-5 AU; P<0.01) and 2 years following the withdrawal of VIT (10+/-3 AU; P<0.05). CONCLUSIONS: In contrast to grass pollen immunotherapy, the persistent decline in venom-specific IgE levels, rather than serum inhibitory activity for FAB, may be more relevant for long-term clinical efficacy of VIT.

Elevated CCR6+ CD4+ T lymphocytes in tissue compared with blood and induction of CCL20 during the asthmatic late response.

CCR6 is expressed by multiple leucocyte subsets, including peripheral blood memory T cells, and mouse models implicate a role for this receptor in diverse inflammatory responses that include allergic airway disorders, inflammatory bowel disease and autoimmune encephalitis. In order to study the role of CCR6 in humans, we have investigated the patterns of CCR6 expression and function on T cells from the peripheral blood, skin, nose and lung, in health and in allergic disease. Results show that CCR6 was expressed consistently on a higher proportion of tissue versus peripheral blood-derived CD4+ T cells (P < 0.01). CCR6 was expressed predominantly on CD4+ compared with CD8+ cells in both blood- and tissue-derived T cells (P < 0.001). The number of cells showing CCR6 expression was not proportionally greater in peripheral blood or nasal mucosal T cells of subjects with symptomatic allergic rhinitis. CCR6+ cells demonstrated enhanced functional responses to CCL20 and CCL20 was increased in bronchoalveolar lavage fluid of asthmatics following endobronchial allergen provocation (P < 0.05). Thus, CCR6 may be important in the regulation of T cell recruitment to tissue and up-regulation of CCL20 expression may contribute to the recruitment and/or retention of effector T cells in allergic asthma.

T lymphocytes expressing CCR3 are increased in allergic rhinitis compared with non-allergic controls and following allergen immunotherapy.

BACKGROUND: In T cell-associated allergic inflammation, homing of T-helper 2 (Th2) effector cells to mucosal sites may be influenced by chemokine receptor expression. Previous studies have identified CCR3 and CCR4 as putative markers of Th2 cells and CCR5 and CXCR3 as markers of Th1 cells. The aim of this study was to assess differential chemokine receptor expression from symptomatic atopic grass pollen-sensitive subjects, compared with patients on high-dose allergen injection immunotherapy (IT) and healthy controls. METHODS: We examined chemokine receptor expression (CCR1-7 and CXCR1-4) by flow cytometry of peripheral blood CD4+ and CD8+ T cells. We also depleted peripheral blood mononuclear cell (PBMC) populations of CCR3+ CD4+ cells by magnetic bead separation and cells were stimulated with grass pollen allergen for 6 days. Cytokine production was measured by enzyme-linked immunosorbent assay. RESULTS: On freshly isolated PBMC, atopic individuals exhibited increased numbers of CCR3+ CD4+ cells compared with normal controls (P < 0.01). CCR3 expression in IT patients was reduced compared with matched atopic rhinitic controls (P < 0.05) and comparable with that observed in normal subjects. Depletion of CCR3+ CD4+ cells from allergen-stimulated PBMC cultures resulted in decreased interleukin (IL)-5 production compared with whole CD4+ populations (P < 0.05). Freshly isolated CCR3+ CD4+ cells have significantly higher intracellular IL-4 and lower IFN-gamma levels than CCR3- CD4+ cells. CD4+ T cells cultured from both peripheral cells and nasal biopsies demonstrated increased expression of CCR3 in the presence of IL-4 (P < 0.05). CONCLUSION: CCR3+ CD4+ T cells are increased in allergic rhinitis, are reduced by allergen IT, have a Th2 phenotype and contribute to allergen-specific responses. Strategies against CCR3+ T cells may be effective in human allergic diseases.

Monophosphoryl lipid A (MPL) promotes allergen-induced immune deviation in favour of Th1 responses.

BACKGROUND: Monophosphoryl lipid A (MPL) is a nontoxic derivative of the lipopolysaccharide (LPS) of Salmonella minnesota R595. MPL has been used as an adjuvant in grass and tree pollen vaccines for the treatment of seasonal allergic rhinitis. Little is known about the influence of MPL on cellular responses to allergens in man. We therefore studied the effects of MPL in vitro on peripheral blood mononuclear cells (PBMC) obtained from patients with grass pollen hay fever. METHODS: The PBMCs from 13 subjects were cultured with grass pollen Phleum pratense extract (0, 2 and 20 microg/ml) and MPL (0 and 10 microg/ml; defined as an optimal concentration in preliminary studies) and after 6 days proliferative responses were measured by thymidine incorporation and cytokine production by enzyme-linked immunosorbent assay (ELISA). RESULTS: Proliferative responses were unaffected by the presence of MPL whereas MPL induced a significant increase in allergen-induced interferon (IFN)-gamma production [allergen alone, 645 +/- 466 pg/ml (mean +/- SE) vs allergen + MPL, 3232 +/- 818 pg/ml; P < 0.001]. In addition, there was a significant decrease in interleukin (IL)-5 production (4307 +/- 1030 pg/ml vs 2997 +/- 826 pg/ml; P < 0.01). Although MPL alone could induce modest increases in IL-10 production, MPL did not influence the production of this cytokine in allergen-stimulated cultures. Addition of neutralizing antibody against IL-12 resulted in 95% inhibition of MPL-induced IFN-gamma production. Depletion of monocytes from the culture system abrogated the effects of MPL on elevated cytokine production. CONCLUSIONS: In summary, use of MPL with grass pollen extract results in immune deviation of allergen-induced peripheral Th2-cell responses in favour of 'protective' Th1 responses in an IL-12 and monocyte-dependent fashion.

Aluminium hydroxide down-regulates T helper 2 responses by allergen-stimulated human peripheral blood mononuclear cells.

BACKGROUND: Aluminium hydroxide (alum) is a commonly used adjuvant for specific immunotherapy of allergic diseases. While alum is traditionally associated with murine Th2 sensitization, little is known about its effects on secondary allergic responses in humans. METHODS: We investigated the in vitro effects of alum on peripheral blood mononuclear cells (PBMC) from atopic donors. PBMC from 18 grass pollen-sensitive rhinitic subjects were stimulated with Phleum pratense (Phl p) in the presence or absence of alum. After 6 days culture, cytokine production was measured by ELISA and T cell proliferation by radiolabelled thymidine incorporation. The effect of alum on the expression of human leucocyte antigen and CD80/CD86 on cultured antigen-presenting cells was assessed by flow cytometry. RESULTS: PBMC cultured with Phl p and alum showed a significant decrease in both IL-5 and IL-13 production compared with allergen alone (P<0.005 and P<0.001, respectively), but no change in IFN-gamma or IL-12 production or proliferative responses. These alum-induced changes in T helper (Th)2 cytokine production were unaffected by the addition of neutralizing antibodies to IL-4 or IL-12. Culture of PBMC with alum induced increased expression of CD86 (P=0.004) and HLA (P=0.01) on monocytes while the expression of CD80 was decreased (P=0.02). SUMMARY: Alum down-regulates allergen-driven Th2 cytokine responses while Th1 cytokines are unaffected. These data confirm that alum is a useful adjuvant for inclusion in allergen immunotherapy vaccines.

CCR4 ligands are up-regulated in the airways of atopic asthmatics after segmental allergen challenge.

T-helper (Th) 2 cytokines are thought to mediate most features of allergic inflammation in atopic asthma. However, it remains unclear whether chemokine pathways direct selective recruitment of Th2 cells to the airways during human allergic responses. Bronchoalveolar lavage (BAL) was performed in 15 nonsmoking mild atopic asthmatics before and 24 h after a fibreoptic segmental allergen challenge, and chemokines related to T-cell recruitment were assayed by ELISA. The Th2-related C-C chemokine (CCR)4 ligands, macrophage-derived chemokine/C-C chemokine ligand (CCL)22 and thymus and activation-regulated chemokine/CCL17, were increased in BAL after challenge. These chemokines correlated significantly with lymphocyte numbers and with interleukin (IL)-5 and IL-13 in post-challenge BAL. In contrast, two out of three putative Th1-related chemokines did not change. There were no alterations in monokine induced by interferon (IFN)-gamma/CXC chemokine ligand (CXCL)9 or macrophage inflammatory protein-1alpha/CCL3; whereas a significant increase in IFN-induced protein-10kDa/CXCL10 was observed, which did not correlate with the T-cell influx. In peripheral mononuclear cells from atopic donors, CCL22 and CCL17 were induced by IL-4 and IL-13, further supporting the relationship between CCL22/CCL17 and Th2 cytokines. Finally, CCL22 was able to trigger actin polymerisation in peripheral CD4+ T-cells expressing CCR4. Thus, C-C chemokine receptor 4 ligands are up-regulated in the airways of atopic asthmatics following allergen exposure, contribute to the T-cell influx to the airways and are closely related to the Th2-cytokine response.

The route of administration of an immunodominant peptide derived from heat-shock protein 65 dramatically affects disease outcome in pristane-induced arthritis.

Previous studies have shown that immunization of mice with an immunodominant epitope from heat-shock protein 65 (hsp 65) (amino acids 261-271) can protect from the development of pristane-induced arthritis (PIA) and this protection is mediated by an antigen-specific T helper type 2 (Th2) cytokine response. Here we confirm these findings and show that frequent intranasal administration of this peptide exacerbates disease. In naive mice given peptide intranasally an antigen-specific T-cell population is systemically activated similar to that induced by peptide immunization in incomplete Freund's adjuvant. Thus, a paradox exists whereby apparently similar peptide-specific populations are either associated with protection from, or exacerbation of, PIA. However, comparison of cytokine profiles reveals differences between these two cell populations. Peptide inhalation induces the production of Th1-type cytokines (interferon-gamma) whereas intraperitoneal immunization leads to the production of Th2-type cytokines (interleukin-4, interleukin-5 and interleukin-10) by splenic T cells upon stimulation with peptide. Thus, for the application of nasal 'tolerance' in clinical medicine, it is important to identify antigens and dosing regimes that counteract but do not activate adverse immune responses.

An immunodominant epitope from mycobacterial 65-kDa heat shock protein protects against pristane-induced arthritis.

Previous studies showed that mice with pristane-induced arthritis (PIA) and those protected from the disease by preimmunization with mycobacterial 65-kDa heat shock protein (hsp65) possess raised immune responses to hsp65. Additionally, T cells from hsp65-protected mice, but not from pristane-injected or normal mice, produced the Th2-associated cytokines IL-4, IL-5, and IL-10 in response to stimulation with hsp65. Here we demonstrate that the specificity of the immune response to hsp65 and related heat shock protein (hsps) differs between protected and PIA mice. T cells from hsp65-protected mice respond to the bacterial hsps tested but not to the mammalian homologue, hsp58. Similarly, they exhibit high serum titers of anti-hsp65 Abs, yet they have virtually undetectable levels of anti-hsp58 IgG. By contrast, both cellular and humoral immune responses are detectable to bacterial and mammalian hsps in mice with PIA. An immunodominant T cell epitope has been identified in hsp65-protected mice corresponding to amino acids 261-271 from hsp65. Immunization of mice, either before or after the induction of arthritis, with this bacterial peptide, but not its mammalian homologue, protects mice from the development of PIA, and protection is associated with the production of Th2-type cytokines. Other experiments revealed that T cells primed with bacterial 261-271 or the mammalian homologue do not cross-react at the proliferative or cytokine level. These results demonstrate that an hsp65 peptide-specific Th2 response confers protection from PIA but do not support the idea that protection is mediated by a cross-reaction with self hsp58 in the joints.

Prospective randomized placebo-controlled trial of aprotinin for elective aortic reconstruction.

BACKGROUND: The serine protease antagonist, aprotinin, reduces perioperative blood loss in cardiac surgery and orthotopic liver transplantation. A pilot study suggested that the drug may also reduce bleeding during infrarenal aortic replacement; the aim was to confirm or refute this observation with a prospective, randomized, double-blind, placebo-controlled trial. METHODS: Some 136 patients were randomized to receive either aprotinin, given as a loading dose of 2 x 10(6) kallikrein inactivator (KI) units followed by 0.5 x 10(6) KI units/h or equal volumes of 0.9 per cent saline. After 80 patients had been randomized the infusion dose was doubled to ensure that plasma levels were similar to those seen in successful cardiac studies. Blood loss, coagulation and haematological parameters were recorded throughout surgery and for 7 days afterwards. Blood was transfused to maintain the haemoglobin level at 100 g/l. RESULTS: Four patients were withdrawn after randomization when found at laparotomy to be unsuitable for the planned reconstruction. The 30-day mortality rate was 4.5 per cent, with no excess complications in either group. Blood loss collected on swabs was reduced from 480 ml in placebo-treated patients to 379 ml with aprotinin (P = 0.014). Blood loss into suction drains in the first 24 h after operation was reduced from 295 to 205 ml in aprotinin-treated patients (P = 0.002). However, no significant reduction was found in intraoperative or total blood loss, or transfusion requirement. CONCLUSION: The small reduction in blood loss in patients treated with aprotinin demonstrated in this study does not support its use in routine elective aortic surgery.

Silicone rubber band treatment of rectal prolapse.

Fifty-two patients with rectal prolapse have been treated by the silicone rubber band perianal suture technique and satisfactory results have been obtained in 46 (89%). Eleven patients required reoperation to achieve this result. The procedure is a minor one, with little morbidity and no mortality. Provided that faecal impaction can be avoided in patients having this operation a successful outcome, can be expected. It is recommended especially for the frail and elderly with rectal prolapse.