2. A clinical study is performed with subjects who developed a skin rash. Skin biopsies from these subjects are analyzed by immunofluorescence. Some of the subjects have the immunofluorescence pattern shown here, with antibody to IgG. This appearance is most likely to be based upon which of the following pathologic mechanisms?

3. A 40-year-old woman has had increasing difficulty swallowing for over the past year. She also notes that she had a condition as demonstrated, and it is more difficult to use the keyboard of her computer because she finds it hard to move her fingers, though the joints are not painful. She has lost the facial wrinkles that she was beginning to develop in middle age. A skin biopsy is performed and shows extensive dermal fibrosis but almost no inflammatory cell infiltrates. These findings are most typical for which of the following conditions?

4. A 40-year-old woman complains of dry mouth and dry eyes that have become almost constantly irritating during the past 2 years, regardless of her fluid intake or the weather outside. Physical examination is shown in the picture. However, her fingers do not turn blue or painful upon exposure to cold. She is found serologically to have autoantibodies to the nuclear antigen SS-A, along with a positive antinuclear antibody test. Which of the following is most likely to be the worst long term complication of her underlying disease?

5. Within minutes after a bee sting, a 15-year-old girl suddenly has difficulty breathing. There is marked urticaria and marked edema of the hand that was stung. Which of the following is the best pharmacologic agent to treat these signs and symptoms?

A 20-year-old woman presents with malar rash, arthralgias, low-grade fever, and high titer antibodies to double-stranded DNA and to the Sm (Smith) antigen. Which of the following forms of hypersensitivity is the primary mechanism of the abnormalities found in this disorder?

An HIV–positive intravenous drug user is suspected of having active tuberculosis, and a tuberculin (Mantoux) intradermal skin test is performed. After 48 hours, 10 cm of induration is observed. Which of the following are involved in this form of hypersensitivity reaction?

A 54-year-old woman is involved in an automobile accident and requires a blood transfusion. Five hours later, she becomes febrile and has severe back pain. Laboratory studies show evidence of intravascular hemolysis. It is discovered that type A Rh+ blood was given by mistake to this type B Rh+ patient. Which of the following best explains the development of intravascular hemolysis in this patient?

A 30-year-old woman complains of impaired speech and frequent aspiration of food. Physical examination reveals diplopia and drooping eyelids. The symptoms of muscle weakness in

this patient are caused by antibodies directed against which of the following cellular components?