[Interleukin 4, total and allergen-specific immunoglobulin E antibodies in the blood of individuals with an atopic constitution].

INTRODUCTION

The recently published data suggest that atopic patients have an enhanced ability to produce IL-4, even in response to antigens other than common environmental allergens or helminthic components. This aberrant IL-4 production by Th cells may be one of the immune alterations encoded by nonMHC genes in the control of basal IgE level [1-7]. The existence of atopen-CD4+ T cell clones that have diverse repertoires might be relevant for aetiopathogenesis of atopic diseases [8-10]. Being subjected continuously to the environmental antigens (allergens), the immune system, especially T cells, is permanently activated and stimulated in response to that challenge. Due to that, substantial amount of diverse cytokines (and their soluble receptors) could be found in the serum. Accordingly, it could be expected to find raised serum IL-4 concentration in atopic persons. In this study we investigated concentrations of IL-4, total IgE and allergen-specific IgE in sera of atopic persons susceptible to pollen allergens. The main goal was to estimate whether the immunologic profile of atopics is defined by increased serum concentration of IL-4 apart from total and allergen-specific serum IgE.

METHODS

Patients. We selected 9 atopic patients in the range of 19-35 years, susceptible to grass or weed pollens and suffering from allergic rhinoconjuctivitis. There were 6 females and 3 males (mean age 31.2 years). Atopic allergy was proven by clinical history, skin prick test and by means of in vitro test (positive serum allergen-specific IgE antibodies, RAST/radioallergosorbent tests [11]. As controls we randomly selected B blood donors (6 females, 2 males, mean age 31.3). Study design. The study was carried out from August till September 1995. None of selected patients had previously accomplished allergen-specific immunotherapy nor had been medicated by corticosteroids (topic or systemic) [12-15]. Selected persons were not allowed to take medications such as antihistamines, beta-2 agonists or tricyclic antidepressants at least 10 days prior to the study. We performed in vitro tests for determining concentrations of IL-4, total and pollen-specific serum IgE. Sera were sampled in the morning and were stored frozen at -20 degrees C until analysis. Determination of IL-4, total and allergen specific IgE in serum. Interleukin-4 measurement was carried out in blind fashion with an ELISA kit (Intertest-4 ELISA, Genzyme, Cambridge) according to the manufacturer's instructions. A reference curve was obtained by plotting the IL-4 concentration of several standard dilutions versus an absorbency. The determination limit was 0.045 pg/ml. For determining total serum IgE we used commercially available enzyme immunoassay (EIA Phadezym IgE PRIST, Pharmacia, Uppsala). Normal values was up to 120 IU/L (international unit per ml). Allergen specific IgE was determined by semiquantitative EIA method (RAST Phadezym, Pharmacia, Uppsala) and expressed in Phadebas RAST Unit (PRU) according to standard curve done by manufacturer. Study was carried out after approval of the Ethic Committee of our Hospital and with the obtained patients consents. For statistical analysis we used nonparametric tests (U-test and the Spearman rank correlation). For all comparisons, statistical significance was considered to be present if p < 0.05.

RESULTS

Among selected patients, 4 persons had high concentration of serum IgE antibodies (RAST class 4) against grass pollens, two persons had IgE-specific (RAST, class 4) to weed pollens and 2 patients had IgE antibodies (RAST class 4) against weed and grass pollens simultaneously. RAST of class 3 was registered in the serum of one person. Registered serum total IgE, allergen-specifc IgE and IL-4 are shown in Table 1. Serum IL-4 was significantly higher in atopics (U-test, SR 43.53, p.05) as well as total IgE (ER 493, p.05). In atopics, IL-4 was not in correlation with either total or allergen-specific IgE (IL-4 versus total IgE, p = +0.190;