Immunoglobulin A only weakly. IgA exists in two isotypes, IgA1 and IgA2. They are both heavily glycosylated proteins. While IgA1 predominates in serum (~80%), IgA2 percentages are higher in secretions than in serum (~35% in secretions); the ratio of IgA1 and IgA2 secreting cells varies in the different lymphoid tissues of the human body: Both IgA1 and IgA2 have been found in external secretions like colostrum, maternal milk, tears and saliva, where IgA2 is more prominent than in the blood. Polysaccharide antigens tend to induce more IgA2 than protein antigens. Both IgA1 and IgA2 can be in membrane-bound form. ("see B-cell receptor")
A Day Called X of downtown called "Operation Greenlight", and the film is often misattributed to that year. Ford's narration, however, does make direct reference to the 1955 exercise. A Day Called X A Day Called X is a dramatized CBS documentary film set in Portland, Oregon, in which the entire city is evacuated in anticipation of a nuclear air raid, after Soviet bombers had been detected by radar stations to the north; it details the activation of the city's civil defense protocols and leads up to the moment before the attack (the ending is left intentionally unknown). The operations were run from the