過敏母親與無過敏母親其初乳之免疫特性

Abstract

雖然哺餵母乳(breastfeeding)普遍被認為可以預防或延後嬰幼兒及孩童日後過敏症狀之出現--- 如: 牛奶蛋白過敏(cow’s milk allergy)、異位性皮膚炎(atopic dermatitis)、過敏性鼻炎(allergic rhinitis)、或氣喘(bronchial asthma)等，但是對其確切之保護效果仍有爭議性，對母乳免疫功能之成份也仍有許多尚待了解及研究之空間。除了做為嬰兒絕佳的營養來源之外，母乳中更含有許多具免疫功能之成份，如：免疫球蛋白( 如： secretory Ig A, IgG )、白血球、多種細胞介質 (cytokines)及其他抑菌成份。嬰幼兒攝食母乳後，這些具免疫調節功能之成份對其尚未發育健全的腸道及未來免疫系統之發展將產生莫大的影響。部分研究顯示: 患過敏疾病之母親和一般無過敏疾病之母親相比，其母乳之免疫成份也不盡相同。一些流行病學研究觀察發現：長期純哺餵母乳之嬰兒若其母親患有氣喘，則其日後發生氣喘之比例也較高。難道有過敏性疾病之母親哺餵母乳反而使其子女的免疫系統導向以第二形輔助T細胞（Th2）為主的反應，而可能對子女造成不良的影響嗎？吾人欲設計一有對照組之研究，比較有過敏疾病之母親和無過敏疾病之母親其母乳(初乳)之免疫特性，並推測母親若有過敏疾病其母乳對子女免疫功能可能之影響。 研究方法: 以問卷收集足月產婦之臨床資料，包括：臨床過敏症狀之有無、年齡、生產方式、懷孕次數、胎次、個人及家族過敏史、及其他因子，如：產婦及其配偶抽煙的情形。抽取母親血液做total IgE, CAP specific IgE 檢驗。根據臨床過敏症狀之有無、母血中serum total IgE及CAP結果，分為過敏組和無過敏組。收集其產後五天內之初乳(colostrum)。初乳細胞成份經Liu stain後在光學顯微鏡下做白血球細胞總數及分類計數。初乳上清液以酵素免疫分析法(enzyme-linked immunosorbent assay, ELISA)測量Th1細胞介質----IFN-γ, IL-12p70, IL-18，及 Th2細胞介質----IL-4, IL-10的濃度。並以ELISA首次測量足月生產之產婦其血清及初乳中decoy receptor 3 (DcR3) 之濃度。 研究結果：共收集到無過敏組產婦60人，過敏組產婦32人。鏡檢下細胞分類成份顯示：絕大多數初乳以充滿脂肪之巨嗜細胞為主(佔90%以上)，餘為少量之淋巴球及嗜中性白血球。本研究中，兩組母乳之白血球細胞總數及白血球細胞分類百分比無顯著之差異；並未發現在過敏組有嗜伊紅性白血球、或嗜鹼性白血球有異常增加之現象。ELISA分析顯示：僅有少數的初乳檢體可以測得到IFN-γ、IL-4及IL-10，且其濃度普遍都低，初乳中較常可測得IL-12p70 (60%)和 IL-18 (70%)。過敏母親與無過敏母親其初乳中之IFN-γ、IL-12p70、 IL-18、 IL-4、 IL-10濃度並無顯著統計上之差異。過敏組母親有較高的比率呈現血清DcR3陽性反應(24.1% vs 43.8%)；且其濃度較無過敏組高(1.88±2.15 ng/ml vs 4.74±7.78 ng/ml, p = 0.014)。母血清DcR3濃度和母血清total IgE濃度呈現顯著正相關，而且只在過敏組有此發現 (r = 0.614, p < 0.001)。兩組各有三至四成的比率可於初乳中測得DcR3。兩組初乳中DcR3濃度無顯著差異 (4.14±9.76 ng/ml vs 6.30±21.77 ng/ml, p = 0.452)。雖然母血清DcR3濃度和其初乳DcR3濃度呈現正相關，但只在無過敏組有此發現（r = 0.293, p = 0.025）。 結論：血清中DcR3含量在過敏產婦較無過敏產婦高。初乳中的白血球細胞總數及細胞分類組成、細胞介質IFN-γ, IL-12p70, IL-18, IL-4, IL-10之濃度，及DcR3含量並未完全反映母親之臨床過敏狀態。DcR3在母乳中的臨床意義還有待進一步的釐清。

Exclusive breast-feeding is relevant to preventing or postponing the development of atopic diseases, such as cow’s milk allergy, atopic dermatitis, allergic rhinitis, and asthma. However, its exact protective effect remains controversial. Individual variations and immunologic complexity in the composition of the breast milk might account for the conflicting findings. The immunologic factors in milk of allergic mothers may differ from that of non-allergic mothers resulting in different effects of breast feeding on offspring’s immunity. The aims of this study are to 1) define the cellular composition of colostrum in allergic and non-allergic mothers, 2) investigate the Th1/Th2 cytokines in colostrum from allergic and non-allergic mothers, 3) define the levels of decoy receptor 3 (DcR3) in serum and colostrum from allergic and non-allergic mothers. From June 2003 to September 2004, specimens of colostrum were obtained from allergic (n=32) and non-allergic (n=60) mothers 3 to 5 days post-partum. Clinical data including maternal age, delivery method, gravida, parity, and parental smoking history were collected. Information about maternal atopy (allergic rhihinitis, atopic dermatitis, and asthma) and family history of atopy were obtained by questionnaires. Maternal blood was analyzed for total IgE, and CAP specific IgE antibodies against common allergens. Subjects were defined as “allergic group” when both antigen-specific antibodies were detected and clinical atopic symptoms were reported. Double negative with atopic history and serology were defined as “non-allergic group”. Milk leucocyte subsets were counted using a light microscopy. By enzyme-linked immunosorbent assay (ELISA) techniques, Th1 cytokines (IFN-r, IL-12p70, IL-18) and Th2 cytokines (IL-4 and IL-10) were investigated in colostrum samples. DcR3 levels in maternal serum and colostrum were also measured by commercial ELISA kit. Most colostrum samples contained large numbers of lipid-filled macrophages (>90%), small numbers of lymphocytes and neutrophils, and scanty basophils and eosinophils. Counts of eosinophils and basophils did not increase in colostrum from allergic mothers. There were no significant differences of total cell counts and percentages of different leucocytes in colostrum between allergic and non-allergic mothers. Low levels of IFN-γ, IL-4, and IL-10 could be detected in a few samples. IL-12p70 (60%) and IL-18 (70%) were more common found in colostrum. All cytokines detected in this study showed no significant differences between the two groups. Serum concentrations of DcR3 were higher in allergic mothers compared with non-allergic mothers (1.88±2.15 ng/ml vs 4.74±7.78 ng/ml, p = 0.014). Significant positive correlation was noted between the levels of serum DcR3 and total IgE level, particularly in the allergic group (r = 0.614, p < 0.001). DcR3 could be detected in 30% to 40% of colostrum samples. There were no significant differences of colostrum DcR3 levels between the two groups. Conclusions: Cellular composition, concentrations of IFN-γ, IL-12p70, IL-18, IL-4, IL-10 and DcR3 in colostrum were not altered by the presence of maternal atopy. DcR3 levels in serum were higher in allergic mothers compared with non-allergic mothers. However, the clinical significance of increased serum DcR3 levels in allergic mothers and the role of milk DcR3 should be further clarified.