Lymphoproliferative responses to dendritic cell presentation of sensitizing allergens in atopic children with multiple allergies.

BACKGROUND: Peripheral blood mononuclear cells (PBMCs) proliferate inconsistently, rendering current lymphoproliferation assays unreliable in diagnosis. OBJECTIVE: To investigate the utility and nature of proliferation responses in allergy by comparison of the standard lymphoproliferation with a new dendritic cell (DC) stimulated assay. METHODS: Monocyte-derived DCs were pulsed with allergens and incubated with autologous T cells for 7 days. DC-stimulated and standard PBMC proliferation responses to 3 common dietary allergens in children with allergy and without atopy were measured by incorporation of tritiated thymidine and reduction of carboxyl fluorescein succinimidyl ester staining. RESULTS: The DC presentation of sensitizing allergens induced significantly higher proliferative responses than PBMC stimulation (P = .04) and greater distinction between normal and allergic responses. DC-induced stimulation indices of children without sensitivity and those with allergy were significantly different with all 3 foods (P < .001). All children with allergy presented with peanut allergy and 12 of 14 (86%) ß-lactoglobulin-pulsed DC preparations proliferated more than 3.3-fold above un-pulsed cells, but 8 of 18 children (44%) with ovalbumin egg allergy showed proliferation below this level. The stimulation index of DC tritiated thymidine incorporation correlated closely with carboxyl fluorescein succinimidyl ester reduction (P < .001). Sensitivity of detection of peanut, milk, or egg allergy was 100%, 85.7%, or 55.6% and specificity was 60%, 88.9%, or 86.7%, respectively. DC-stimulated T cells expressed increased levels of CD45 RO and CD25 and most produced interferon-γ. DC-stimulated proliferation correlated with total immunoglobulin E and peanut antigen-stimulated proliferation correlated with peanut specific immunoglobulin E (P = .03). CONCLUSION: The DC-induced lymphoproliferation had higher sensitivity, specificity, and reproducibility than the standard assay and caused increased memory and activated T-cell proliferation in children with food allergy.

Correlation of allergen-specific IgG subclass antibodies and T lymphocyte cytokine responses in children with multiple food allergies.

Cytokines can affect the quantity and class of allergen-specific immunoglobulins through the T cell polarization that accompanies atopy. Antigen-specific IgG subclasses and IgE antibodies were compared with intracellular T cell cytokine changes to sensitizing antigens in 23 children with multiple food allergies and 20 healthy controls. Allergic children showed higher levels of total and food-specific IgE, IgG1 and IgG4 to peanut, milk and egg than non-atopic children or adults, coinciding with a TH2 cytokine response to sensitizing antigens. IgG1 and IgG4 antibodies specific to milk and egg and peanut protein were elevated relative to age-matched healthy children (p