Allergy transfer with hematopoietic cell transplantation from an unrelated donor

Two cases of eosinophilic gastrointestinal disorder due to newly appearing food allergies after cord blood transplantation

Eosinophilic gastrointestinal disorders (EGIDs) are infrequent complications after allogeneic hematopoietic cell transplantation (allo-HCT). Furthermore, it is well-known that allergic diseases are transferable after allo-HCT from allergic donors to non-allergic recipients. However, the type of graft-versus host disease (GVHD) prophylaxis that leads to allergic disease transfer is unclear. Furthermore, no study has reported a case of acquired food allergy resulting in EGID that was detected based on the clinical course and the detection of antigen-specific immunoglobulin E after allo-HCT. We encountered two patients with acute leukemia accompanied by eosinophilic esophagitis (EoE) and eosinophilic gastroenteritis (EGE) due to newly appearing food allergy after cord blood transplantation (CBT) with T-cell non-depletion GVHD prophylaxis. Despite having no history of allergic disease, the patients experienced allergic symptoms due to dairy products (Case 1) and eggs (Case 2) after CBT. They subsequently experienced severe nausea, heartburn, and anorexia (Case 1) and diarrhea (Case 2). Cases 1 and 2 were diagnosed with EoE and EGE, respectively, based on endoscopic and histological examinations. Dietary treatment without steroids improved the symptoms in both cases. These cases highlight that the unexpected transfer of food allergy after CBT can lead to EGIDs, especially in patients receiving T-cell non-depletion GVHD prophylaxis.

Development of New White Fish Allergy after Bone Marrow Transplantation from a Non-atopic Donor

Background: Transplant-acquired food allergy has become increasingly recognized in solid organ and bone marrow transplantation. As food allergy has no cure and causes considerable impact on the lives of patients who require strict avoidance of foods to avoid potentially severe or fatal reactions, it is crucial for physicians to better understand the risk factors and mechanisms driving development of food allergy post-transplant. We report a case of new food allergy to whitefish in an elderly patient post-bone marrow transplant in which neither donor nor recipient had a history of atopy. Methods: A 70-year-old man experienced an anaphylactic reaction to Swai whitefish (Pangasius hypophthalmus) 6 months post-transplant that he had previously tolerated on multiple occasions both pre-transplant and in the preceding months post-transplant. This allergy was investigated by commercial serum specific IgE testing and fresh prick-to-prick skin test to Swai whitefish. Results: Fresh prick-to-prick demonstrated large positive reaction to the Swai whitefish with wheal of 10 mm and flare of 22 mm compared to positive histamine control with a wheal/flare of 5x8mm. Serum specific IgE testing to commercial whitefish was negative (specific IgE <0.10kU/L). The patient continues to strictly avoid Swai whitefish but tolerates all other fish and shellfish. Conclusions: The unique development of specific Swai whitefish allergy in an elderly man after bone marrow transplant where both donor and recipient had no prior history of atopy strongly supports transplant-related immunomodulation as a major mechanism for transplant-acquired allergy and suggests that that absence of atopy or advanced age may not necessarily be protective.

Transfer and loss of allergen-specific responses via stem cell transplantation: A prospective observational study

BACKGROUND

Currently, no estimates can be made on the impact of hematopoietic stem cell transplantation on allergy transfer or cure of the disease. By using component-resolved diagnosis, we prospectively investigated 50 donor-recipient pairs undergoing allogeneic stem cell transplantation. This allowed calculating the rate of transfer or maintenance of allergen-specific responses in the context of stem cell transplantation.

METHODS

Allergen-specific IgE and IgG to 156 allergens was measured pretransplantation in 50 donors and recipients and at 6, 12 and 24 months in recipients post-transplantation by allergen microarray. Based on a mixed effects model, we determined risks of transfer of allergen-specific IgE or IgG responses 24 months post-transplantation.

RESULTS

After undergoing stem cell transplantation, 94% of allergen-specific IgE responses were lost. Two years post-transplantation, recipients' allergen-specific IgE was significantly linked to the pretransplantation donor or recipient status. The estimated risk to transfer and maintain individual IgE responses to allergens by stem cell transplantation was 1.7% and 2.3%, respectively. Allergen-specific IgG, which served as a surrogate marker of maintaining protective IgG responses, was highly associated with the donor's (31.6%) or the recipient's (28%) pretransplantation response.

CONCLUSION

Hematopoietic stem cell transplantation profoundly reduces allergen-specific IgE responses but also comes with a considerable risk to transfer allergen-specific immune responses. These findings facilitate clinical decision-making regarding allergic diseases in the context of hematopoietic stem cell transplantation. In addition, it provides prospective data to estimate the risk of transmitting allergen-specific responses via hematopoietic stem cell transplantation.

B Cell Responses in the Development of Mammalian Meat Allergy

Studies of meat allergic patients have shown that eating meat poses a serious acute health risk that can induce severe cutaneous, gastrointestinal, and respiratory reactions. Allergic reactions in affected individuals following meat consumption are mediated predominantly by IgE antibodies specific for galactose-α-1,3-galactose (α-gal), a blood group antigen of non-primate mammals and therefore present in dietary meat. α-gal is also found within certain tick species and tick bites are strongly linked to meat allergy. Thus, it is thought that exposure to tick bites promotes cutaneous sensitization to tick antigens such as α-gal, leading to the development of IgE-mediated meat allergy. The underlying immune mechanisms by which skin exposure to ticks leads to the production of α-gal-specific IgE are poorly understood and are key to identifying novel treatments for this disease. In this review, we summarize the evidence of cutaneous exposure to tick bites and the development of mammalian meat allergy. We then provide recent insights into the role of B cells in IgE production in human patients with mammalian meat allergy and in a novel mouse model of meat allergy. Finally, we discuss existing data more generally focused on tick-mediated immunomodulation, and highlight possible mechanisms for how cutaneous exposure to tick bites might affect B cell responses in the skin and gut that contribute to loss of oral tolerance.

Tracing IgE-Producing Cells in Allergic Patients

Immunoglobulin E (IgE) is the key immunoglobulin in the pathogenesis of IgE associated allergic diseases affecting 30% of the world population. Recent data suggest that allergen-specific IgE levels in serum of allergic patients are sustained by two different mechanisms: inducible IgE production through allergen exposure, and continuous IgE production occurring even in the absence of allergen stimulus that maintains IgE levels. This assumption is supported by two observations. First, allergen exposure induces transient increases of systemic IgE production. Second, reduction in IgE levels upon depletion of IgE from the blood of allergic patients using immunoapheresis is only temporary and IgE levels quickly return to pre-treatment levels even in the absence of allergen exposure. Though IgE production has been observed in the peripheral blood and locally in various human tissues (e.g., nose, lung, spleen, bone marrow), the origin and main sites of IgE production in humans remain unknown. Furthermore, IgE-producing cells in humans have yet to be fully characterized. Capturing IgE-producing cells is challenging not only because current staining technologies are inadequate, but also because the cells are rare, they are difficult to discriminate from cells bearing IgE bound to IgE-receptors, and plasma cells express little IgE on their surface. However, due to the central role in mediating both the early and late phases of allergy, free IgE, IgE-bearing effector cells and IgE-producing cells are important therapeutic targets. Here, we discuss current knowledge and unanswered questions regarding IgE production in allergic patients as well as possible therapeutic approaches targeting IgE.

Developments in the field of allergy in 2016 through the eyes of Clinical and Experimental Allergy

In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2016. Experimental models of allergic disease, basic mechanisms, clinical mechanisms, allergens, asthma and rhinitis, and clinical allergy are all covered.

B cells establish, but do not maintain, long-lived murine anti-peanut IgE(a)

BACKGROUND

Peanut allergy (PNA) has been reported to be transferred to tolerant recipients through organ and bone marrow (BM) transplantation. The roles T and B cells play in establishing, and the roles B cell subsets play in maintaining lifelong anti-peanut IgE levels are unknown.

OBJECTIVES

To determine the cellular requirements for the transfer of murine PNA and to determine the role CD20(+) cells play in maintaining long-lived anti-peanut IgE levels.

METHODS

We developed a novel adoptive transfer model to investigate the cellular requirements for transferring murine PNA. We also treated peanut-allergic (PA) mice with anti-CD20 antibody and measured IgE levels throughout treatment.

RESULTS

Purified B220(+) cells from PA splenocytes and purified CD4(+) cells from naïve (NA) splenocytes are the minimal requirements for the adoptive transfer of PNA. Prolonged treatment of allergic mice with anti-CD20 antibody results in significant depletion of B cell subsets but does not affect anti-peanut IgE levels, symptoms, or numbers of IgE antibody secreting cells (ASCs) in the BM. Adoptive transfer of BM and spleen cells from allergic donors treated with anti-CD20 antibody does not result in the transfer of PNA in NA recipients, demonstrating that anti-CD20 antibody treatment depletes B cells capable of differentiating into peanut-specific IgE ASCs.

CONCLUSIONS AND CLINICAL RELEVANCE

Peanut allergy can be established in a NA hosts with B220(+) cells from PA donors and CD4(+) cells from peanut-NA donors. However, long-term depletion of B220(+) cells with anti-CD20 antibody does not affect anti-peanut IgE levels. These results highlight a novel role for B cells in the development of PNA and provide evidence that long-lived anti-peanut IgE levels may be maintained by long-lived ASCs.

Hematopoietic stem and progenitor cells in inflammation and allergy

Hematopoietic stem and progenitor cells contribute to allergic inflammation. Pro-inflammatory cytokines that are generated following allergen challenge can impact the differentiation of hematopoietic progenitor cells leading to increased production of effector cells such as eosinophils and basophils, which are key cells involved in the pathogenesis of allergic airway inflammation. Homing of stem cells to the lungs is associated with inflammatory and remodeling changes in asthmatics. Factors that modulate the differentiation and increased migration of stem cells to the site of inflammation in asthma remain to be defined. Stem cells can mature at the site of inflammation in response to inflammatory mediators and other components in the milieu. While the available data suggest that hematopoietic cells traffic to target tissues, the molecular factors underlying in situ differentiation have yet to be specified. Here, we critically evaluate the potential role of hematopoietic progenitors in contributing to the increased immune cell infiltrate in allergic asthma and the factors that drive their differentiation.

New developments in transplant-acquired allergies

Transplant-acquired allergy (TAA) was firstly described as transplant-acquired food allergy (TAFA) after bone marrow transplantations and mostly observed in a transient form. The picture is complicated by numerous case reports of TAFA after the receipt of liver grafts from donors with no documented history of food allergy. The estimated prevalence of TAFA among young children in the literature has been documented in various studies ranging from 6% to 57%. Although TAA is mostly found to be associated with liver transplantation; it has been recently reported to be related with heart, intestinal, lung and even renal transplantations in adults. Previous reviews of published cases of liver TAA misleadingly emphasized the predominance of children and the absence of TAA in cardiac, pulmonary, and renal transplant recipients. In different studies, the male/female ratio is equal. Literature data suggest that children with TAFA typically present within the first year after surgery and are typically allergic to multiple foods. The pathogenesis of TAA is not still completely understood. Most of the studies support the concept that the functioning liver itself, and not only tacrolimus immunosuppression, is one of the main contributors to TAA in these patients. In the light of recent findings, other possible mechanisms can be summarized as following: (1) the recovery of delayed type hypersensitivity; (2) late manifestation of food allergy; (3) intestinal injury as well as inhibition of cellular energy production by tacrolimus; and (4) transfer of food-specific IgE or lymphocytes. Thus, interplay between hematopoietic cells from the transplanted organ and recipient specific factors (e.g., younger age and atopic background) seem to underlie the development of TAA. Most patients will have symptomatic improvement following reduced immunosuppression and an appropriately restricted diet. Nevertheless, some studies suggest that atopic diseases occur in some of pediatric liver transplant recipients, with manifestations including food allergy, eczema, allergic rhinitis, and asthma. More studies would be needed including greater number of patients to determine whether TAA is transient or not in pediatric/adult solid organ recipients.

Immune reconstitution after hematopoietic cell transplantation

PURPOSE OF REVIEW

Successful immune reconstitution is important for decreasing posthematopoietic cell transplant (post-HCT) infections, relapse, and secondary malignancy, without increasing graft-versus-host disease (GVHD). Here we review how different parts of the immune system recover, and the relationship between recovery and clinical outcomes.

RECENT FINDINGS

Innate immunity (e.g., neutrophils, natural killer cells) recovers within weeks, whereas adaptive immunity (B and T cells) recovers within months to years. This has been known for years; however, more recently, the pattern of recovery of additional immune cell subsets has been described. The role of these subsets in transplant complications like infections, GVHD and relapse is becoming increasingly recognized, as gleaned from studies of the association between subset counts or function and complications/outcomes, and from studies depleting or adoptively transferring various subsets.

SUMMARY

Lessons learned from observational studies on immune reconstitution are leading to new strategies to prevent or treat posttransplant infections. Additional knowledge is needed to develop effective strategies to prevent or treat relapse, second malignancies and GVHD.

Cell-based therapy in allergy

IgE-mediated allergy is an immunological disorder occurring in response to otherwise harmless environmental antigens (i.e., allergens). Development of effective therapeutic or preventive approaches inducing robust tolerance toward allergens remains an unmet goal. Several experimental tolerance approaches have been described. The therapeutic use of regulatory T cells (Tregs) and the establishment of molecular chimerism are two cell-based strategies that are of particular interest. Treg therapy is close to clinical application, but its efficacy remains to be fully defined. Recent proof-of-concept studies demonstrated that transplantation of syngeneic hematopoietic stem cells modified in vitro to express a major allergen leads to molecular chimerism and robust allergen-specific tolerance. Here we review cell-based tolerance strategies in allergy, discussing their potentials and limitations.