IgG4 anti-infliximab in treated patients: Clinical impact and temporal evolution.

BACKGROUND: Infliximab (IFX) carries potential risk of immunogenicity with the production of anti-drug antibodies (ADA). ADA may belong to different isotypes and are usually measured by ELISA bridging assay. This test is not designed to detect IgG4 antibodies. The aim was to measure IgG4 anti-IFX antibodies in a cohort of IFX-treated patients and to evaluate their relationship with ADA and their clinical impact. METHODS: Anti-drug antibodies were detected using a bridging ELISA in the serum of 222 treated patients with different clinical outcomes to IFX. The same samples were analyzed for IgG4 anti-IFX antibodies using an experimental ImmunoCAP assay with reduced serum IgG4 background levels. A longitudinal evaluation was performed in a subgroup of 38 patients to define the temporal evolution of IgG4 anti-IFX. RESULTS: IgG4 anti-IFX was found in 26.6% of patients. Eighty of 222 patients were ADA+ (36%) and the majority (57/80, 71.3%) had IgG4 anti-IFX. Two IgG4-positive but ADA-negative patients were identified. IgG4 anti-IFX levels correlated with the serum levels of ADA. IgG4 anti-IFX was more common in both reactive and nonresponder patients than in tolerant/responder patients. Patients who had experienced IgE-mediated reactions displayed significantly higher IgG4 anti-IFX than IgE-negative reactive patients. The majority of patients tested positive for IgG4 anti-IFX after the first seven infusions. CONCLUSIONS: IgG4 anti-IFX is common in treated patients and a large part of ADA producing patients produce IgG4 antibodies. The IgG4 anti-IFX response does not prevent hypersensitivity reactions to IFX and correlates with the IgE anti-IFX response.

Measurement of specific IgE antibodies to Ses i 1 improves the diagnosis of sesame allergy.

BACKGROUND: The number of reported cases of allergic reactions to sesame seeds (Sesamum indicum) has increased significantly. The specific IgE tests and skin prick tests presently available for diagnosis of sesame allergy are all based on crude sesame extract and are limited by their low clinical specificity. Thus, oral food challenge (OFC) is still the gold standard in the diagnosis. OBJECTIVE: The aim was to identify the allergen components useful to diagnose sesame-allergic children with the goal to reduce the number of OFCs needed. METHODS: Ninety-two sesame-sensitized children were consecutively enrolled and diagnosed based on OFC or convincing history. Specific IgE to purified native 11S globulin (nSes i 11S), 7S globulin (nSes i 7S), 2S albumin (nSes i 2S), and two recombinant 2S albumins (rSes i 1 and rSes i 2) was measured by ELISA and/or ImmunoCAP (rSes i 1/streptavidin application). RESULTS: Based on area under curve (AUC) values from receiver operating characteristic (ROC) analysis, rSes i 1 was shown to have the best diagnostic performance of the allergen components in ELISA. The experimental rSes i 1 ImmunoCAP test had larger AUC (0.891; 95% CI, 0.826-0.955) compared to the commercially available sesame ImmunoCAP (0.697; 95% CI, 0.589-0.805). The clinical sensitivity and specificity for the rSes i 1 ImmunoCAP test at optimal cut-off (3.96 kUA /L) were 86.1% and 85.7%, respectively. CONCLUSION AND CLINICAL RELEVANCE: Sensitization to Ses i 1 is strongly associated with clinical sesame allergy. Measurement of specific IgE to rSes i 1 could reduce the numbers of OFCs needed.

High IgE levels to α-lactalbumin, ß-lactoglobulin and casein predict less successful cow's milk oral immunotherapy.

BACKGROUND: A new treatment option for persistent cow's milk allergy (CMA) is oral immunotherapy (OIT). Not all patients develop tolerance during therapy, and markers to identify those who will benefit from it are needed. The objective was to study the IgE and IgG4 antibody profiles to milk and milk proteins before and after OIT in relation to clinical outcome. METHODS: Seventy-six children (5-17 years) with challenge-verified CMA were subjected to a 6-month OIT protocol. The treatment aimed at reaching a maintenance dose of 200 ml CM (high dose = HD). Those who did not reach target were analysed as a low-dose (LD) group. Sera were characterized before and after OIT regarding serum levels of IgE and IgG4 to milk and five milk allergen components evaluated together with clinical CMA symptoms and outcome of OIT. RESULTS: Fifty-five (72%) patients reached the maintenance dose (HD) during therapy. High specific IgE levels towards the milk allergens α-lactalbumin (P = 0.048), ß-lactoglobulin (P = 0.006) and casein (P = 0.015) before OIT start were associated with lower maintenance dose reached. Patients who developed desensitization had a larger increase in IgG4 levels to α-lactalbumin (P = 0.034), ß-lactoglobulin (P = 0.010), casein (P = 0.047) and lactoferrin (P = 0.030) during treatment than those who failed. CONCLUSIONS: Component-resolved diagnostics before OIT can help to identify children with lower probability of a successful OIT outcome, as high IgE levels to α-lactalbumin, ß-lactoglobulin and casein are associated with lower maintenance dose reached. An increase in the IgG4 concentration to milk components during treatment indicated effective desensitization.

Characterization of anti-natalizumab antibodies in multiple sclerosis patients.

BACKGROUND: A small proportion of multiple sclerosis (MS) patients treated with natalizumab develop anti-drug antibodies. OBJECTIVE: The objective of this paper is to characterize the anti-natalizumab antibody response and to investigate differences between persistently and transiently antibody-positive patients. METHODS: Screening for anti-natalizumab antibodies was performed using a standardized bridging ELISA. Antibody-positive samples were further analyzed for IgM and IgG1-4 antibodies using ELISA and ImmunoCAP®. RESULTS: Anti-natalizumab antibodies developed in 57 of 1379 (4.1%) treated patients after a median treatment duration of three months. Of the positive patients, 20 (35%) patients reverted to negative, 19 (33%) patients were confirmed persistently positive and 18 (32%) patients were unconfirmed positive. Significantly higher anti-natalizumab antibody levels were detected in persistently compared to transiently positive patients. A cutoff value predicting persistence of antibodies could be determined with a sensitivity of 0.84 and a specificity of 0.80. IgM and IgG4 antibody levels were significantly higher in persistently compared to transiently positive patients, and IgG1, IgG2 and IgG4 increased significantly over time. CONCLUSIONS: The level of total anti-natalizumab antibodies in a first positive sample can be used to predict patients at risk for persisting antibody positivity. However, neither IgM nor IgG1-4 antibodies could be used to discriminate between transiently and persistently positive patients.

IgE to peanut allergen components: relation to peanut symptoms and pollen sensitization in 8-year-olds.

BACKGROUND: Allergen-specific IgE testing is often performed with crude peanut extract, but the results may be difficult to interpret because of cross-reactions between peanut and other plant allergens. The aim was to investigate IgE reactivity to peanut allergen components in children from a birch-rich region in relation to pollen sensitization and peanut symptoms. METHODS: From a birth cohort, clinical parameters were obtained through questionnaires and IgE antibody levels to peanut and birch pollen were measured. Different peanut/birch sensitization phenotypes were defined among 200 selected children. IgE reactivity to peanut and pollen allergen components was analysed using microarray technique. RESULTS: Peanut symptoms were reported in 87% of the children with IgE reactivity to any of the peanut allergens Ara h 1, 2 or 3 but not to Ara h 8 (n = 46) vs 17% of children with IgE reactivity to Ara h 8 but not to Ara h 1, 2 or 3 (n = 23), P < 0.001. Furthermore, symptoms were more severe in children with Ara h 1, 2 or 3 reactivity. Children with IgE reactivity both to Ara h 2 and to Ara h 1 or 3 more often reported peanut symptoms than children with IgE only to Ara h 2 (97%vs 70%, P = 0.016), particularly respiratory symptoms (50%vs 9%, P = 0.002). CONCLUSIONS: IgE analysis to peanut allergen components may be used to distinguish between peanut-sensitized individuals at risk of severe symptoms and those likely to have milder or no symptoms to peanut if sensitized to pollen allergens and their peanut homologue allergens.

Change in the pattern of IgE reactivity to timothy grass and birch pollen allergens over a 20-year period.

BACKGROUND: Several studies have shown that the prevalence of allergy and allergen sensitization has increased in recent years. However, the changes in the pattern of IgE reactivity to individual allergens are mostly unknown. OBJECTIVE: The aim of this preliminary study was to assess the change in IgE reactivity profile to individual timothy grass and/or birch pollen allergens in sera from sensitized individuals randomly collected 20 years apart. METHODS: Serum samples from 51 sensitized individuals were obtained from 2 cross-sectional surveys performed in 1973 and 1994 using random samples from Vammala, Finland. The sera were analyzed for IgE reactivity to timothy grass and/or birch pollen extracts, recombinant (r)Phl p 1, 2, 5, 6, 7, 11, 12, native (n)Phl p 4, and rBet v 1, 2 and 4 by immunoassay (ImmunoCAP). RESULTS: The median (range) concentrations of IgE antibodies to timothy grass and birch pollen were higher in 1994 than in 1973 (6.47 [0.35 to >100] kU A/L vs 1.53 [0.40-25.3] kU A/L; P=.0035). The prevalence of IgE reactivity to some allergens was higher in 1994 than in 1973, particularly rPhl p 5 (52% vs 19%), rPhl p 6 (43% vs 12%), and rBet v 1 (100% vs 29%). There was a correlation between timothy grass pollen-specific serum IgE levels and the numbers of IgE reactivities to individual allergens (p=0.76, P<.001). CONCLUSIONS: The increase in specific IgE levels together with a possible increase in the prevalence of IgE reactivity to the major allergens Phl p 5 and Bet v 1 between 1973 and 1994 may have contributed to the increase in atopic conditions in Finland.

Pollen-specific rush immunotherapy: clinical efficacy and effects on antibody concentrations.

BACKGROUND: Studies of rush immunotherapy (RIT) with standardized extracts for the treatment of seasonal pollen allergy are few, especially for birch-pollen RIT. OBJECTIVE: The study was performed to investigate the efficacy of RIT with standardized birch- or timothy-pollen extracts. Further, the serum antibody levels were evaluated for correlation with clinical efficacy. METHODS: This open, longitudinal study included 30 allergic patients treated with RIT and 16 allergic patients serving as a control group. The therapy was continued for 3 years and blood samples were collected at regular intervals for antibody measurements using the Pharmacia CAP System. RESULTS: The RIT was generally well tolerated. An increase in the total and specific IgE concentrations during the early months of RIT was observed, followed by decreased levels. Specific IgG and IgG4 increased continuously for 2 years. The symptom and medication scores were significantly decreased, compared with preRIT, at both the first and third pollen seasons after the start of RIT treatment (P < .0001 and P < .001, respectively). The clinical improvement during RIT was significantly greater compared with the control group (P < .05). The decreased medication and the symptom improvement during the third year of RIT correlated with the relative decrease in specific IgE (rs = .52, P < .05) and with the specific IgG4 level before the start of RIT (rs= -.68, P < .01), respectively. CONCLUSIONS: Our study indicates that RIT with standardized birch- or timothypollen extracts is clinically effective and safe. Measurements of specific antibody levels during treatment may be helpful in monitoring RIT.

Cytokine production by peripheral blood mononuclear cells following birch-pollen immunotherapy.

We studied the Th2/Th1 balance by short-term stimulation of peripheral blood mononuclear cells (PBMC) isolated during the pollen season from seven allergic patients treated with conventional birch-pollen immunotherapy (IT) for 18 months, eight matched allergic control patients and 10 non-atopic individuals. The PBMC were cultured for 7 days with birch-pollen extract (BPE) or tetanus toxoid (TT), and then restimulated with PHA and PMA to induce high IL-5, IL-10 and IFN-gamma production. The serum levels of birch-pollen-specific IgG and IgG4 were significantly elevated after IT treatment. The proliferative response to BPE was significantly enhanced in the allergic control group, but not in the IT-treated group, compared to the non-atopic group (P<0.05). Birch-pollen-specific IL-5 production was significantly enhanced in both the IT-treated group and the allergic control group (P<0.01-0. 05). Furthermore, both the IT-treated group and the allergic control group had a cytokine profile to BPE significantly more Th2 polarized (high IL-5/IFN-gamma ratio) than to TT (P<0.05 and P<0.01, respectively). No differences in IL-10 production between the three study groups were observed. The Th2/Th1 balance in vitro correlated with the serum concentrations of birch-pollen-specific IgE (r=0.60, P<0.05), and in the IT-treated group, also with the IgG and IgG4 levels (r=0.79, P<0.05 and r=0.86, P<0.05, respectively). We conclude that conventional birch-pollen IT does not lead to changes in the cytokine profile of the circulating pool of allergen-specific T cells during birch-pollen season. However, induction of peripheral T-cell tolerance and increased production of specific IgG and IgG4 might be part of the mechanisms of IT.

Changes in cytokine production in vitro during the early phase of birch-pollen immunotherapy.

The kinetics of the immunological mechanisms during allergen-specific immunotherapy (IT) has not been thoroughly evaluated. In this investigation we study the changes in T-cell responses during the early phase of IT. Ten patients (IT group) with birch-pollen allergy were treated with conventional IT. Blood samples were collected at regular intervals for specific immunoglobulin (Ig)E measurements and preparation of peripheral blood mononuclear cells (PBMC). Seven allergic control patients (AC group) were included during the subsequent birch-pollen season. The PBMC were stimulated with birch-pollen extract or tetanus toxoid (TT) and mitogens. After a short decrease, probably owing to seasonal variation, the birch-pollen-specific proliferation and the interleukin (IL)-4, IL-5, and IL-10 production significantly increased when reaching the maintenance dose and during the subsequent pollen season. The increase in IL-4 correlated with a temporary increased serum level of birch-pollen-specific IgE. Interestingly, also the TT-specific response was affected by IT, resulting in weaker, but in time similar, changes in proliferation and cytokine production as in the birch-pollen-specific response. We speculate that the early phase of IT might lead to systemic changes in the capacity of Th2-like cytokine production, and that the early increase in allergen-specific IgE is a consequence of enhanced IL-4 production.

Study of the Th1/Th2 balance, including IL-10 production, in cultures of peripheral blood mononuclear cells from birch-pollen-allergic patients.

BACKGROUND: Excessive production of interleukin (IL)-4, IL-5, IL-10, and IL-13 is thought to be important in the development of allergy and asthma. The objective of this investigation was to study Th1/Th2-like cytokine profiles in vitro in seven patients allergic to birch pollen and six nonallergic controls during the birch-pollen season. METHODS: Peripheral blood mononuclear cells (PBMC) were isolated and cultured with birch-pollen extract (BPE) or tetanus toxoid (TT) for 7 days, harvested, and restimulated with the mitogens phytohemagglutinin (PHA) and phorbol 12-myristate 13-acetate (PMA) for 24 h. Cytokine production was determined by ELISA, and logarithmic cytokine ratios were compared between the two groups and between the antigens. RESULTS: In the allergic group, the cultures prestimulated with BPE had a more Th2-like cytokine response than the TT-prestimulated cultures; i.e., lower IFN-gamma and higher IL-10 production (P<0.05), as well as higher IL-5/IFN-gamma and IL-13/ IFN-gamma ratios (P<0.05). There were also significantly higher IL-4/IFN-gamma (P<0.005) and IL-5/IFN-gamma (P<0.05) ratios in BPE-stimulated cultures in the allergic group than in the control group. The IL-4 and IL-13 production in vitro correlated with the specific serum IgE levels. CONCLUSIONS: BPE stimulation induces a Th2-like cytokine response by PBMC isolated during the pollen season from birch-pollen-allergic patients, indicating a Th2-type immune response to birch pollen in vivo.

Allergen-specific increase in interleukin (IL)-4 and IL-5 secretion from peripheral blood mononuclear cells during birch-pollen immunotherapy.

The mechanisms behind the effects of immunotherapy (IT) with birch-pollen extract are largely unknown. In this pilot study, we measured the cytokine secretion in vitro from peripheral blood mononuclear cells (PBMC) obtained from birch-pollen-allergic patients undergoing IT treatment (n = 4) or placebo administration (n = 4), collected before treatment, 1 and 4 weeks after start of treatment, and during and just after the pollen season (12-14 weeks after start of treatment). The PBMC were stimulated with birch-pollen extract in vitro for 7 days, followed by restimulation with the mitogens phytohemagglutinin (PHA) and phorbol 12-myristate 13-acetate (PMA) for 24 h, to enhance the production of cytokines. The supernatants were analyzed with ELISA and radioimmunoassay for interferon-gamma (IFN-gamma), interleukin (IL)-4, and IL-5. In the therapy group, we noted an increased secretion of IL-4 and IL-5 from PBMC collected at 4 weeks after the start of treatment (IL-4: 29 +/- 21 pg/ml [day 0] to 374 +/- 448 pg/ml [week 4], mean +/- SD; IL-5: 95 +/- 48 pg/ml to 1147 +/- 697 pg/ml). No increase was seen in the placebo group. During the pollen season, we noted a trend toward increased IL-4 and IL-5 secretion in both groups. We conclude that the temporary increase in serum IgE observed in many IT studies may be a consequence of increased IL-4 production due to the allergen exposure.