下条 直樹

正常乳児を対象として, 生直後よりの栄養 (母乳, 調整粉乳, アミノ酸乳) により便粘液細胞診中に出現してくる好酸球の出現状況を半年間観察し, 消化管アレルギー (ミルクアレルギー) 患者のそれと比較し, 以下の結果を得た。(1) 二親等以内にアトピー歴がない正常乳児においては, 哺乳開始後の移行便中にハンセル染色陽性顆粒を有する細胞 (好酸球) が, 一過性に出現し1週間以内にほぼ消失した。(2) 哺乳内容にかかわらず (母乳, 調整粉乳, アミノ酸乳), 便粘液中好酸球は出現した。(3) 母乳哺乳児は調整粉乳に, またアミノ酸乳哺乳児は母乳に変更すると再び一過性に多量の好酸球の出現が認められたがすぐに消失した。その後同量の調整粉乳を与えても好酸球の出現は認められなかった。(4) 両親が強いアトピー素因を有する乳児において, 母乳から調整粉乳に変更した際に多量の好酸球が出現し, さらに好酸球数の低下が正常乳児に比較して遷延化した。(5) ミルクアレルギーを起こしている患児では便粘液中に多量の好酸球が常に認められた。調整粉乳又は母乳を除去すると臨床症状の改善と共に減少または消失した。また抗原と思われる調整粉乳, 母乳を再び経口負荷すると好酸球は増加を示し, 哺乳を中止しない限り持続的に便中に多量に出現した。以上より, 正常乳児とミルクアレルギー患児では便粘液中に出現する好酸球の動態が異なることが示された。この結果は, ミルクを原因とする消化管アレルギーの診断においてのみならず, 正常乳児の食物抗原に対する免疫応答を考える上でもきわめて重要な結果と考えられた。

In order to investigate the role of food antigen-specific T cells circulating in the blood of patients with food allergy, we compared T cell response to three casein components (αs-, β- and, K-casein) with specificities of IgG and IgE binding to the casein components in four milk-allergic patients (P1-4) with atopic dermatitis. In all patients, the binding activities of IgG antibodies to αs-casein were most dominant, followed by those to β- and to K-casein. The major component of casein bound by IgE antibodies was αs-casein in P1 and P3, K-casein in P2, and αs-casein as well as K-casein in P4 the order of casein components bound by IgE antibodies was different from that by IgG antibodies. Proliferative responses of peripheral blood mononuclear cells (PBMC) to casein components were so low that the dominance of casein recognition could not be clearly demonstrated. However, short-term T cell lines that specifically respond to casein were successfully established from PBMC of the four patients and the proliferative responses of the T cell lines to the three components of casein were in accord with the IgE antibody specificity to casein components but not with that of IgG antibody specificity. When taken together, these results indicate that casein-specific T cells circulating in the blood are involved in or reflect an allergic reaction against casein. 1997 Japan Pediatric Society.

A multiplicity of TSH receptor autoantibodies (TSHRAbs) have been characterized after subcloning heterohybridomas produced from the lymphocytes of a patient who has Hashimoto's thyroiditis and had three children with intrauterine or neonatal hyperthyroidism. Twelve clones produced stimulating TSHRAbs that increased cAMP levels and iodide uptake in rat FRTL-5 thyroid cells and increased cAMP levels in Chinese hamster ovary (CHO) cells transfected with the human TSHR like 95% of Graves' stimulating TSHRAbs, all 12 have their functional epitope on the N-terminus of the TSHR extracellular domain, requiring residues 90-165 for activity. All 12 bind to human thyroid membranes in the absence, but net the presence, of TSH, but are only weak inhibitors of TSH binding in assays measuring TSH binding-inhibiting Igs (TBIIs). In contrast, 8 different clones produced TSHRAbs that did not increase cAMP levels, but, instead, exhibited significant TBII activity. Four inhibited the ability of TSH or a stimulating TSHRAb to increase cAMp levels and had their functional epitope on the C-terminal portion of the TSHR external domain, residues 261-370, mimicking the properties of blocking TSHRAbs that cause hypothyroidism in patients with idiopathic myxedema. The 4 other TBIIs inhibited the ability of TSH, but not that of a stimulating TSHRAb, to increase cAMP levels, like TBIIs in Graves' patients. The functional epitope for 3 of these Graves'-like TBIIs was residues 90-165 the functional epitope for the fourth was residues 24-89. The fourth also increased arachidonic acid release and inositol phosphate levels in FRTL-5 thyroid cells and exhibited conversion activity, i.e. the ability to increase cAMP levels in the presence of an anti-human IgG. Thus, this TBII exhibited signal transduction activity, unlike the other 3 Graves'-like TBIIs. The patient, therefore, has stimulating TSHRAbs and 3 different types of TBIIs, each with different functional properties and different epitopes on the TSHR.

We studied allergenic determinants that induce hypersensitivity to OVA, the major allergen in egg allergy, using immunoblot and histamine release assays. Immunoblot analysis demonstrated a part of the OVA epitope was in the C-terminal region comprising residues 347-385 (OVA347-385). Histamine was released from basophils of a patient with egg allergy upon stimulation with the OVA fragment corresponding to OVA347-385. Furthermore, detailed epitope mapping using overlapping peptides (residues 347-366, OVA-A residues 357-376, OVA-B and residues 367-355, OVA-C) in the OVA 347-385 region was carried out using the histamine release assay. In order for histamine release from basophils to occur, the allergen must possess two or more allergenic determinants located on the protein molecule at distances that would be equivalent to the distances between IgE molecules on the membrane surface. These results suggest that there are at least two epitopes that bind IgE antibodies on each OVA peptide. In addition, one epitope that binds IgE antibodies in two patients appears to reside in the haptenic peptide OVA357-366 (OVA-B1). The histamine release from basophils stimulated by OVA-B was completely inhibited by OVA-B I in one of these patients. Similarly, OVA-B1 inhibited the histamine release produced by OVA-A in the other by more than 40%. These results suggest that haptenic synthetic peptides could regulate the allergic reaction in the effector phase if common epitope(s) recognized by IgE antibodies in the patients with egg allergy can be found. These are the first studies that provide an antigen-specific approach to inhibiting histamine release from basophils by a haptenic peptide recognized by IgE antibodies in an allergic disorder.

生後半年〜12歳までの気管支喘息患者39名を対象として, 鼻粘膜スメア細胞診を行い, スメア上に出現している肥満細胞, 好酸球, 好塩基球の出現とRAST法によるダニに対するIgE抗体価との関連を解析し, 以下の結果を得た. (1) 鼻粘膜スメア細胞診上での好酸球の出現数はダニに対するRASTスコアと明らかな相関が認められた. (2) ダニ抗原に対する感作が血清学的に検出されるよりも以前に, また鼻粘膜スメア好酸球の出現に先だって, 鼻粘膜スメア上に肥満細胞の出現が観察された. (3) 好塩基球は, 好酸球の出現してきた症例においてのみ, 好酸球が出現してきた後に認められた. 以上より, 鼻粘膜スメア細胞診はアレルギー反応が起こる粘膜局所での細胞の動態を観察でき, 特に肥満細胞の存在は気道アレルギー疾患における局所でのアレルギー性炎症を早期に診断する方法として, 有用と考えられた.