保护肠粘膜对付非侵袭性细菌及其产物的抗体,可来自血清和肠固有层的浆细胞等两个来源。从血清中得到抗体的机制似乎不起作用,因为抗体保护水平只有在血清抗体滴度很高时才能达到,这种现象极少是能长期维持的。进入肠腔的血清抗体主要是IgG,但固有层浆细胞局部产生的抗体一般都是IgA,由隐窝上皮选择性地分泌到粘膜表面。由于分泌性IgA耐受肠道酶类的蛋白水解作用,因而这种对粘膜表而保护作用的安排,似乎比IgG好。 Antibodies that protect the gut mucosa against non-invasive bacteria and their products can come from both sources, serum and the lamina propria plasma cells. The mechanism by which antibodies are obtained from serum does not seem to work because the level of antibody protection is only reached when serum antibody titer is very high, which is rarely sustained over the long term. Serum antibodies entering the intestine are predominantly IgG, but antibodies locally produced by lamina propria are typically IgA secreted selectively by the crypt epithelium to the mucosal surface. Because secreted IgA is resistant to the proteolytic action of intestinal enzymes, this arrangement of protective effects on the mucosal surface seems to be better than that of IgG.