Oral desensitization in children with immunoglobulin E-mediated cow's milk allergy – follow-up at 4 yr and 8 months

Until now, the basic treatment for food allergy has been to avoid the offending item. This approach is difficult in the case of common foods and in the case where there is a risk of severe reaction after consuming the offending food, even inadvertently. This is the follow‐up of a previous study aimed at desensitizing 21 children with immunoglobulin E (IgE)‐mediated cow’s milk (CM) allergy. This protocol was totally or partially successful in 85% of cases, but failed in the remaining 15%. Our aims were to study the long‐term effectiveness and safety of oral CM desensitization, and the prognostic value of Skin Prick Test (SPT) and specific serum CM IgE. The 21 children were called back (one dropped out). The allergic history and other information on CM intake over the last 4–5 yr were recorded. Children underwent SPT, and end‐point SPT, with casein and α‐lactoalbumin. Specific CM IgE was also measured. At follow‐up, 14/20 children totally (n = 13, 65%) or partially (n = 1, 5%) tolerated CM. None of the recalled children reported use of emergency care. SPT positivity to casein and/or α‐lactoalbumin decreased significantly (p < 0.01), and all the negative SPT referred to the tolerant children. Cutaneous sensitivity to both casein and α‐lactoalbumin (end‐point SPT) significantly decreased after the 6‐month desensitization period of the previous study (p < 0.001), but did not decrease significantly at follow‐up. A significant reduction of serum‐specific CM IgE was also observed (p < 0.05). Clinical tolerance induced by oral CM desensitization persists in time. Negativization of SPT and reduction of specific CM IgE could be considered prognostic indicators of CM tolerance. Oral CM desensitization seems to be a promising method to treat CM food allergy. This protocol is time‐consuming but offers the advantage that it can be performed at home. This methodology must only be used by trained staff.     

Specific oral tolerance induction in childhood

Food allergy continues to be a significant public health concern for which there are no approved treatments and management strategies primarily include allergen avoidance and pharmacological measures for accidental exposures. Food allergy is thought to result from either a failure to establish oral tolerance or the breakdown of existing oral tolerance, and therefore, experimental preventative and treatment strategies are now aimed at inducing specific oral tolerance. This may occur in infancy prior to the development of food allergy through the optimal timing of dietary exposure (primary oral tolerance induction) or as a treatment for established food allergy through oral immunotherapy (secondary oral tolerance induction). Trials examining the effectiveness of early dietary allergen exposure to prevent food allergy have yielded promising results for peanut allergy but not so for other allergens, although the results of several trials are yet to be published. Although infant feeding guidelines no longer advise to avoid allergenic foods and exposure to food allergens orally is an important step in inducing food tolerance by the immune system, evidence regarding the optimal timing, dose and form of these foods into the infant's diet is lacking. Likewise, oral immunotherapy trials appear promising for inducing desensitization; however, the long‐term efficacy in achieving sustained desensitization and optimal protocols to achieve this is unknown. More research is needed in this emerging field.     

Immune response of young children using ATP‐based Cylex® assay: A brief report

Jayaram A, Zeevi A, Bentlejewski C, Lin Y, Michaels MG. Immune response of young children using ATP‐based Cylex^® assay: A brief report. Pediatr Transplantation 2010: 14:664–666. © 2010 John Wiley & Sons A/S. Abstract: Data on immune responses of young children using ATP release–based Cylex assay are insufficient. This study measured the immune response of healthy children less than three years of age to mitogens, PHA and Con‐A. Blood was obtained from children attending routine health care visits. The Cylex^® assay was used to measure ATP production by CD4+ and CD3+ cells in response to PHA and Con‐A, respectively. Samples from 20 children less than three years (range 10–27 months) were evaluated. The mean ATP production by CD4+ lymphocytes following PHA stimulation was 376 ng/mL (95% CI 17.1–735), which was similar to the response of older children in Hooper et al.’s (Clin Transplant 2005;19:834) study (p‐value 0.28). The mean and median ATP production by CD3+ cells following Con‐A stimulation were 114 ng/mL and 93.3 ng/mL, respectively (95% CI for median 45.2,148.6). The data suggest that although the immune system of young infants and toddlers is evolving, they are still able to respond to mitogen stimulation similar to older children.     

Munc13‐4 deficiency with CD5 downregulation on activated CD8+ T cells

Familial hemophagocytic lymphohistiocytosis (FHL) is characterized by uncontrolled activation of T cells and macrophages and hypercytokinemia. We have recently described a significant increase in a subpopulation of CD8⁺ T cells with downregulation of CD5 during the acute phase of FHL type2 (FHL2; perforin deficiency), which declines after successful treatment, with a concomitant reduction in serum cytokine level. This unusual subset of CD8⁺ T cells, however, has not been characterized in patients with other subtypes of FHL. Herein, we describe a patient with FHL3 (Munc13‐4 deficiency) carrying compound heterozygous mutations in the UNC13D gene. He had high serum levels of pro‐inflammatory cytokines and significantly increased activated CD8⁺ T cells with downregulation of CD5 during the acute phase, similar to that found in FHL2. This immunophenotypic feature may serve as a useful marker of immune dysregulation in FHL3 in addition to FHL2.     

Severe,persistent, and fatal T‐cell immunodeficiency following therapy for infantile leukemia

We describe five cases of children who completed chemotherapy for infantile acute lymphoblastic leukemia (ALL) and soon after were diagnosed with severe T‐cell, non‐HIV immunodeficiency, with varying B‐cell and NK‐cell depletion. There was near absence of CD3⁺, CD4⁺, and CD8⁺ cells. All patients developed multiple, primarily opportunistic infections. Unfortunately, four patients died, although one was successfully treated by hematopoietic stem cell transplantation. These immunodeficiencies appeared to be secondary to intensive infant ALL chemotherapy. Our report highlights the importance of the early consideration of this life‐threatening immune complication in patients who received chemotherapy for infantile ALL.     

Spezifische orale Toleranzinduktion bei Nahrungsmittelallergie

Specific oral tolerance in food allergy can be induced by oral administration of gradually increasing dosages of the offending food. So far, only a few studies on a limited number of patients are available. However, these show good results regarding cow’s milk and hen’s egg allergies, with high efficacy rates and without relevant side effects so far. This article gives an overview of the published studies, provides insight into possible immunological backgrounds, describes different patterns of reaction, and discusses the pros, cons, and possible implications of specific oral tolerance induction (SOTI). At present, SOTI cannot be administered routinely in daily practice. However, in the near future, SOTI could be an alternative to the strict elimination diets presently used, with the advantages of better quality of life and increased safety for the patients. Controlled, long-term studies using larger numbers of patients are needed in order to show who could profit from SOTI and to understand the underlying immunological mechanisms.     

A probiotic dairy product containing L. gasseri CECT5714 and L. coryniformis CECT5711 induces immunological changes in children suffering from allergy

The increase in the prevalence of allergic diseases in children has been attributed to an unbalanced immune response probably due to environmental factors. The immunoregulatory properties of probiotic bacteria could balance the disequilibrium in the immune response causing the allergic response. The aim of this study was to evaluate the immunological effects of the consumption of a dairy product containing two probiotic strains in children suffering from allergy. A double‐blinded, randomized, control comparative study was performed with 44 allergic children. Children were randomly distributed in two groups, a control Yogurt and a Probiotic group. Both groups daily consumed 200 ml of a dairy fermented product for 3 months. The Yogurt group consumed a conventional yogurt, whereas the Probiotic group consumed a similar dairy product where Lactobacillus bulgaricus was substituted by a mixture of Lactobacillus gasseri CECT5714 and Lactobacillus coryniformis CECT5711 (at least 10⁶ cfu/g each strain). Intestinal and immunological parameters were measured in fecal and blood samples. The consumption of the probiotic product induced a significant decrease in the level of IgE in plasma (p = 0.03) and an increase in CD4⁺/CD25⁺ T regulatory cells (p = 0.01). The decrease in IgE was accompanied by a significant increase in mucosal IgA (p = 0.01). However, changes in other effector cells potentially involved in allergic reactions such as eosinophiles, basophiles or other IgE+ cells were not detected. The consumption of the probiotic product also induced significant changes in innate response as a significant increase in natural killer cells was detected (p = 0.03). The daily consumption of a probiotic product containing L. gasseri CECT5714 and L. coryniformis CECT5711 for 3 months induces, in allergic children, beneficial effects on immune parameters involved in the allergic response such as a reduction of IgE in plasma and an increase in regulatory T cells. The probiotic product also enhanced innate and specific immune parameters that may improve the general health status of children.     

Determination of T‐cell subpopulations and intracellular cytokine production (interleukin‐2, interleukin‐4, and interferon‐γ) by cord blood T‐lymphocytes of neonates from atopic and non‐atopic parents

This report describes the results of a prospective study on immunological markers in cord blood for the prediction of allergic diseases in children. First we evaluated methodological aspects of the flow cytometric technique on cord blood cytokine measurements. Subsequently, the T‐cell subsets and percentage of cytokine‐producing cord blood T‐helper (Th) and T‐suppressor/cytotoxic lymphocytes of neonates from atopic and non‐atopic parents were compared. A group of 33 healthy, full‐term newborn infants of whom 23/33 were at risk for atopy (i.e. having at least one parent with one or more atopic symptoms and positive specific immunoglobulin E [IgE] to at least one common inhalant allergen) was studied. A flow cytometric technique was used to analyze cord blood T‐cell subsets and to determine the percentage of interleukin (IL)‐2‐, IL‐4‐, and interferon‐γ (IFN‐γ)‐producing cord blood Th and T‐suppressor/cytotoxic lymphocytes following stimulation with phorbol 12‐myristate 13‐acetate (PMA) and ionomycin. The percentage of CD3 (T lymphocytes), CD3⁺ CD4⁺ (Th lymphocytes), CD3⁺ CD8⁺ (T‐suppressor/cytotoxic lymphocytes), CD19⁺ (B lymphocytes), CD3⁺ CD4⁺ CD45RO⁺ (memory Th lymphocytes), and CD3⁺ CD4⁺ CD45RA⁺ (naive Th lymphocytes) cells was unrelated to parental atopic status. PMA stimulation augmented the percentage of IL‐2‐ and IFN‐γ‐producing Th and T‐suppressor/cytotoxic lymphocytes, whereas the number of IL‐4‐producing T lymphocytes remained very low or undetectable. No differences in the percentage of IL‐2‐, IL‐4‐ and IFN‐γ‐producing Th and T‐suppressor/cytotoxic lymphocytes were found between neonates from atopic and non‐atopic parents. These results will be re‐evaluated when the atopic status of the children at the age of 1 and 2 years can be assessed.     

Protein‐losing enteropathy and erythema caused by egg allergy in a breast‐fed infant

A 4‐month‐old breast‐fed girl presented with poor weight gain, and had edema and repeated erythema from 5 months of age. The diagnosis of protein‐losing enteropathy (PLE) was confirmed on ^99mTc‐labeled human serum albumin scintigraphy. Specific IgE radioallergosorbent test was class 3 for egg white, class 2 for egg yolk, and negative for other foods. Elimination of egg from the mother's diet and oral epinastine hydrochloride treatment and sodium cromolyn improved hypoalbuminemia, hypogammaglobulinemia, and erythema. PLE and erythema coincident in a breast‐fed infant suggests that IgE‐mediated allergy may play a leading role in some cases of PLE due to food allergy in infants.     

Expression of and responses to CD2 and CD3 in 18‐month‐old children with and without atopic dermatitis

We hypothesize that atopy is associated with a reduced T‐cell function early in life and an imbalance in cytokine production. The purpose of this study was to investigate the expression of and responses to CD2 and CD3 in children who did or did not develop atopic dermatitis early in life. The expression of CD2 and CD3 was analyzed by flow cytometry, and proliferation of CD2 and CD3 was studied by ³H‐thymidine incorporation in phytohaemagglutinin (PHA)‐ and anti‐CD3‐stimulated peripheral blood mononuclear cells (PBMC) of 18‐month‐old children, 25 with and 29 without atopic dermatitis. Exogenous interleukin (IL)‐2 was added to compensate for possible functional differences in accessory cells. Anti‐CD3‐induced secretion of IL‐4, IL‐5, IL‐6, IL‐10, IL‐13, and interferon‐γ (IFN‐γ) was analyzed by enzyme‐linked immunosorbent assay (ELISA). Atopy was associated with a low proportion of CD2⁺ lymphocytes. Responsiveness to PHA, which activates lymphocytes partly via the sheep erythrocyte receptor, CD2, was reduced in the allergic children. The anti‐CD3‐induced proliferation declined more rapidly with antibody dilution in the allergic than in the non‐allergic children. Atopic dermatitis was associated with high levels of anti‐CD3‐stimulated IL‐5 secretion. The IL‐4/IL‐10 and IL‐4/IFN‐γ ratios were higher in children with elevated total immunoglobulin E (IgE) levels. Skin prick test‐negative children with eczema produced higher levels of IL‐10 than skin prick test‐positive children. In conclusion, atopic children have a reduced T‐cell function. Atopic dermatitis is associated with increased IL‐5 production, while high total IgE levels are associated with high IL‐4/IFN‐γ and IL‐4/IL‐10 ratios.     

Demonstration of type II latency in T lymphocytes of Epstein–Barr Virus‐associated hemophagocytic lymphohistiocytosis

Epstein–Barr virus (EBV) is the most common infectious cause of non‐genetic hemophagocytic lymphohistiocytosis (HLH). To investigate EBV‐infected lymphocytes and immune dysfunction in EBV‐associated HLH, blood samples from a 6‐year‐old boy were longitudinally analyzed using molecular techniques. EBV‐positive lymphocytes were detected as CD5⁺, CD8⁺, and/or HLA DR⁺ lymphocytes on Day 25 of the disease, mostly disappearing thereafter. CD8⁺ cells specific for lytic antigen BRLF1 were detected, but cells specific for latent antigens EBNA3 and LMP2 were not. EBV genes EBNA1, LMP1, LMP2, EBER1, BARTs were detected, suggesting a latency type II gene expression pattern in this case. Pediatr Blood Cancer 2013;60:326–328. © 2012 Wiley Periodicals, Inc.     

Low frequency of CD4+, but not CD8+, T cells expressing interferon‐γ is related to cow's milk allergy in infancy

Low interferon‐γ (IFN‐γ) and tumor necrosis factor‐α (TNF‐α) production in peripheral blood mononuclear cells (PBMC) from patients with atopic dermatitis and food allergy have been reported previously. However, it remains unclear whether the weak cytokine production is caused by the imbalance of specific T‐cell subsets or by dysregulation of T‐cell function. In the present study we investigated the intracellular expression of these cytokines at a single‐cell level to clarify the background of the disruption. Twelve of 27 breast‐fed infants (0.1–8.8 months of age) had challenge‐proven cow's milk allergy (CMA), and 15 infants were studied as a healthy control group. PBMC were stimulated with phorbol 12‐myristate 13‐acetate (PMA) and ionomycin. The frequencies of the cells expressing intracellular IL‐4, IFN‐γ, and TNF‐α were assessed using flow cytometry. In addition, at this time‐point leucocyte subsets from the milk of mothers of these infants were evaluated using light microscopy. A lower number of CD8⁺ T cells and the defective capability of CD4⁺ T cells to express IFN‐γ in infant's peripheral blood co‐existed with a lower number of macrophages in their mother's milk.     

Mass cytometry reveals a distinct immunoprofile of operational tolerance in pediatric liver transplantation

Long‐term IS in transplant patients has significant morbidity, poorer quality of life, and substantial economic costs. TOL, defined as graft acceptance without functional impairment in the absence of IS, has been achieved in some pediatric LT recipients. Using mass cytometry, peripheral blood immunotyping was performed to characterize differences between tolerant patients and patients who are stable on single‐agent IS. Single‐cell mass cytometry was performed using blood samples from a single‐center pediatric LT population of operationally tolerant patients to comprehensively characterize the immune cell populations in the tolerant state compared with patients on chronic low‐dose IS. Specific T‐cell populations of interest were confirmed by flow cytometry. This high‐dimensional phenotypic analysis revealed distinct immunoprofiles between transplant populations as well as a CD4⁺ TOT (CD4⁺CD5⁺CD25⁺CD38^?/loCD45RA) that correlates with tolerance in pediatric LT recipients. In TOL patients, the TOT was significantly increased as compared to patients stable on low levels of IS. This TOT cell was confirmed by flow cytometry and is distinct from classic Treg cells. These results demonstrate the power of mass cytometry to discover significant immune cell signatures that have diagnostic potential.     

Peroxisome proliferator‐activated receptor γ 2 mutation may cause a subset of ulcerative colitis

Aim: Previous studies suggest the homeostasis between acquisition of tolerance to the indigenous microflora and protective immune responses appears to be disrupted in inflammatory bowel disease (IBD). Some experimental studies indicate peroxisome proliferator‐activated receptor γ (PPARγ) has been implicated as a regulator of intestinal inflammatory responses. In addition, the toll‐like receptor (TLR)‐4 can regulate expression of PPARγ in colonic epithelial cells. We attempted to demonstrate whether the functional imbalance between TLRs and PPARγ could lead to the onset and some polymorphisms of those genes could contribute to susceptibility to IBD. Methods: RT‐PCR analysis were performed to detect TLR4 and PPARγ mRNA associated with those of P65 of NFκB, TNFα, MyD88, NOD2/CARD15, TLR‐2,5,9, in the diseased colonic mucosa in ulcerative colitis (UC; n = 13) and Crohn's disease (CD; n = 7) compared with normal controls (n = 18). Consequently, we genotyped UC (n = 29) and CD (n = 10) compared with normal controls (n = 134) for the prevalence of suspicious mutations. Results: In a subset of UC patients who were revealed to carry PPARγ Pro12Ala mutation later, impaired expression of normal PPARγ mRNA was noted in the diseased mucosa accompanied with upregulations of MyD88 TLR‐4, 5, 9, P65 and TNFα in mRNA levels. The prevalence of PPARγ Pro12Ala mutation was more frequently found in UC patients compared with CD patients and normal controls (P < 0.05). Conclusions: These findings suggested that imbalances between TLRs and PPARγ in response to luminal bacteria could lead to colonic inflammation in some UC patients. Alternative explanations will be needed for the onset of the rest of UC and CD.     

Specific oral desensitization in children with IgE-mediated cow's milk allergy. Evolution in one year

Cow's milk allergy is the most frequent childhood food allergy. Children older than 5 who have not become tolerant have less probabilities of natural tolerance. Specific oral desensitization methods are being investigated in reference centres. The aims of our study were to assess the efficacy of our guideline of specific oral desensitization to cow's milk in children and to know its suitability for anaphylactic children. Both clinical and specific IgE outcomes were evaluated. Eighty-seven children aged 5 to 16?years with a history of cow's milk allergy were included. Prior to desensitization, skin prick test, specific IgE to cow's milk proteins and a double-blind placebo control food challenge were performed in all. Of the 87 patients, 21 had a negative challenge; they were considered tolerant, and they were told to follow a free diet. Of the positive, 44 were anaphylactic and 22 non-anaphylactic. All of them were included. In non-anaphylactic patients, 6 achieved partial and 16 maximum desensitization after 23.1?weeks. In the anaphylactic group, 7 achieved partial and 35 maximum desensitization after 26.4?weeks. Cow's milk-specific IgE levels and casein-specific IgE levels were significantly lower in the tolerant patients at baseline. One year after desensitization, the medium specific cow's milk levels and casein IgE levels had dropped significantly. Conclusions: Our guideline for specific oral desensitization to cow's milk is efficacious even in patients with anaphylactic reactions to cow's milk and represents a significant life change. Immunological changes in 1?year show a drop in cow's milk protein-specific IgE.     

Two color flow cytometric analysis of lymphocytes in HTLV-I-carrier children

Phenotypic changes in lymphocytes from healthy children with antibody for human T lymphotrophic virus type I (HTLV-I) were studied using two color flow cytometry. The subjects were high school students within a small district of Kyushu, Japan. In the carrier group, a subset of lymphocytes which expressed CD8⁺CD57⁺ was significantly lower in percentage (P < 0.01) and in number (P < 0.05). There was no significant difference between carriers and non-carriers in the percentage and number of CD4⁺ Leu8⁺cells or CD4⁺ HLA-DR⁺ cells. The IgG levels were slightly higher in carriers than in non-carriers (P < 0.05). These findings suggest that HTLV-I-infected cells may affect the immune system in healthy carrier children.     

Chemotherapy‐induced B‐cell depletion in hepatoblastoma patients undergoing ABO‐incompatible living donor liver transplantation

LT from ABO‐I donors requires preconditioning regimens to prevent postoperative catastrophic AMR. NAC for HBL is known to cause myelosuppression leading to a reduction in the number and function of lymphocytes. We investigated this chemotherapy‐induced myelosuppression in HBL patients listed for LT from ABO‐I donors with reference to the kinetics of B, T cells, and anti‐ABO blood type isoagglutinin titers. Between 2005 and 2015, of the 319 patients who underwent LDLT at our institute, 12 were indicated for unresectable HBL. Three patients with unresectable HBL who underwent LDLT from ABO‐I donors are included in this study. Immunosuppression consisted of a standard regime of tacrolimus and low‐dose steroids as in ABO compatible/identical LDLT. No additional preoperative therapies for B‐cell depletion were used. Absolute lymphocyte counts, lymphocyte subsets (including CD20+ B cells, CD3+CD4+ T cells and CD3+CD8+ T cells), and anti‐ABO blood type isoagglutinin titers were measured before LDLT and postoperatively. The median age at diagnosis was 19 months (range, 3–31 months). The median follow‐up was seven months (range, 6–15 months). The median interval from the last NAC to LDLT was 33 days (range, 25–52 days). The median interval from LDLT to adjuvant chemotherapy was 28 days (range, 22–36 days). The counts of CD20+ B cells before LDLT were depleted to median 5 cells/mm³ (range, 0–6 cells/mm³). There was a transient rebound in the CD20+ B cell counts on day seven (maximum of 82 cells/mm³) followed by a decline starting at 14 days after LDLT that was sustained for the duration of adjuvant chemotherapy. Anti‐ABO blood type isoagglutinin titers were lowered to between 1:1 and 1:16 before LDLT and remained low for the duration of follow‐up in this study. All of the three patients remained in good health without either acute cellular or AMR after LDLT. The B‐cell depletion that occurs after cisplatin‐based chemotherapy for HBL may help accomplish safe ABO‐I LDLT in children without the use of additional conditioning regimens for prevention of AMR.     

Development of natural tolerance and induced desensitization in cow’s milk allergy

Cow’s milk allergy (CMA) affects 2–3% of infants. It resolves in the great majority spontaneously during childhood. CMA encompasses a spectrum of clinical and immunologic characteristics. Non‐IgE‐mediated allergy typically resolves earlier than IgE‐mediated allergy. The most documented prognostic characteristic is that intense‐specific IgE response predicts persistence of CMA. Low serum levels of cow’s milk (CM)‐specific IgG4 are also associated with persistent CMA. Natural development of tolerance involves an immunologic shift where Th2 responses diminish, and Th1 as well as T regulatory cell responses strengthen. Accordingly, specific IgE levels decrease and specific IgG4, possibly also IgA, levels increase in serum. Specific oral immunotherapy (OIT) with CM induces desensitization in most cases where spontaneous recovery has not yet occurred. Data on long‐term tolerance induction are still scarce. According to current research data, the immunologic changes induced by OIT resemble those seen during natural development of tolerance.     

Immunotherapy – risk/benefit in food allergy

Food allergy is a growing health concern in the westernized world with approx. 6% of children suffering from it. A lack of approved treatment has led to strict avoidance of the culprit food proteins being the only standard of care. Nowadays in‐depth research is conducted to evaluate the possible use of allergen‐specific immunotherapy (SIT) as an active therapeutic option for food allergy. Various routes of administration for the immunotherapy are investigated, including subcutaneous, oral, sublingual, and epicutaneous, and some appear to be successful in inducing a temporary tolerant state. Most research has been conducted with oral immunotherapy due to its efficacious and relatively safe profile. Increasing interest is dedicated to safer and more convenient approaches, such as sublingual and epicutaneous SIT; however, doubts exist about their possible capacity to induce temporary tolerant state and permanent oral tolerance. The high frequency of allergic adverse reactions of the various approaches and the inability to achieve permanent oral tolerance have highlighted the need of refinements in the strategies. A promising strategy for preventing IgE cross‐linking and thus enhancing safety of SIT, while still activating T cells, is the use of tolerogenic peptides. The implementation of such an immunotherapy approach has the potential of not only increasing the chance of achieving a permanent state of tolerance, but also improving the safety and tolerability of the therapy. Immunotherapy for food allergy is still not ready for the clinic, but current and upcoming studies are dedicated to collect enough evidence for the possible implementation of allergen‐SIT as a standard treatment for food allergy.     

Defective tumor necrosis factor-α production in infants with cow’s milk allergy

As an aid to clarifying the role of immune mechanisms in the development of cow’s milk allergy (CMA) in suckling infants, we studied the capacity of peripheral blood mononuclear cells (PBMC) to produce tumor necrosis factor-α (TNF-α) in vitro. The study population consisted of 43 infants, aged 0.12–11.2 months; of these, 31 had challenge-proven cow’s milk allergy manifested with either skin or gastrointestinal symptoms or both. In addition, 12 healthy infants were studied as controls. The spontaneous, unstimulated and mitogen-induced production of TNF-α and interferon-γ (IFN-γ) by isolated peripheral blood leukocytes was evaluated. TNF-α and IFN-γ production of PBMC was significantly lower in infants with cow’s milk allergy than in healthy children. Our results indicate that, in infants with CMA, the function of TNF-α-producing cells is defective. This might disturb the development of oral tolerance and thereby lead to cow’s milk allergy. These results may help to clarify the etiopathology of CMA.