硬皮症是一種全身性自體免疫疾病，主要特徵是其組織纖維母細胞會過度的分泌膠原。從過去的文獻，以知Topo I(topisomerase I)抗體及抗中節抗體在硬皮症的特異性，同時也發現在硬皮症病人，其染色體之斷裂有增加之現象，這些結果顯示硬皮症的發生與細胞內的抗原有密切的關係。至於這些細胞內的抗原如何進到細胞間質或血液循環中，並進一步引發自體免疫抗體的機轉，則尚無任何理論或實驗能以解釋。
如果將纖維母細胞培養再固定的collagen gel內時，細胞會附著並且伸展於纖維之中，呈現兩極伸長的型態。再經過一些時間，纖維母細胞便開始將膠原纖維重整，收縮collagen gel，使gel的厚度變薄，並使其中的細胞處於張力緊繃的狀態。但若以外力解除此一張力，則會引發一連串的反應，其中包括了一種特殊的膜泡外分泌(ectocytosis)，可將細胞內的物質包於膜質小泡內分泌至細胞外。
所以，我們的實驗變利用此一模式，設計將硬皮症病人纖維母細胞培養在collagen gel內48小時，然後以外力解除細胞緊繃的張力，促使纖維母細胞進行膜泡外分泌(ectocytosis)。經由利用低速和超高速的離馨將此過程分泌的膜質小泡分離而收集。再經由SDS-PAGE以及和80位自體免疫疾病及10位正常人的血清進行免疫點墨法分析，結果顯示三種分子為硬皮症血清特別認識。其分子量及陽性反應頻率分別為12-14kd(19/43),32-34Kd(31/43),77-80Kd(23/43)。其中32-34Kd經進一步研究後證實為annexins。這是一種新的發現，這些結果顯示細胞內分子可能擔任硬皮症的病因角色，同時代表ectocytosis可能是呈現出自體免疫抗原給免疫系統認識的一個新的機轉。
Scleroderma is a systemic autoimmune disorder characterized by fibrosis and over-production of extracellular matrix components by some population of fibroblasts. Most of the intracellular disorders in sclerotic fibroblasts are still not elucidated in detail.
Previously , we have known the roles and the specificity of topoisomerase I antibodies and anticentromere antibodies in patients with scleroderma. And also found an increased occurrence of chromosome breakages in patients with scleroderma. These results indicate that there are some relationships between the pathogenesis of scleroderma and intracellular autoantigens.
Ectocytosis , the release of sorted cellular protenins in the from of enriched membrane vesicles,can be triggered by relaxing the tension posed upon fibroblasts.
In the present study, we are tempted to test the possibility that if proteins ectocytosed from non-immune cells might be an alternative source of autoimmunogens.
The fibroblasts from scleroderma patients were cultured in a three-dimentional ,histotypic matrix composed of type I collagen fibrils. Membrance vesicles relased by SDS-PAGE,and immunblotted with sera from 80 autoimmune patients and 10 normal volunteers.Three major polypeptides 12-14Kda,32-34Kda,77-80Kda,are prominent bands on SDS-PAGE and immunoblots.Among which, the 32-34Kda polypeptide has been further identified as annexins,the lipid-,actinbinding, and calcium-dependent protenins.Our data suggest that ectocytosis from non-immune cells might play an important role in the generation of autoantigens.
