Immunopathology — Past Paper OmpathStudy

Immunopathology — Questions and Answers Complete review bank: 39 questions recovered from all 26 source pages. The source numbering omits Question 37. 1. A 15-year-old healthy girl with no major medical problems notes blotchy areas of erythema that are pruritic over the skin of her arms, legs, and trunk within an hour every time she eats seafood, followed by diarrhea. These problems abate within 3 hours, and then physical examination reveals no abnormal findings. Which of the following immunologic abnormalities is she most likely to have? A. Localized anaphylaxis B. Cell-mediated hypersensitivity C. Complement activation D. Hypergammaglobulinemia E. Immune complex deposition Answer: A. Food allergies are typically a form of type I hypersensitivity reaction. The allergens react with IgE bound to mast cells mainly located in dermis of skin and submucosa of gastrointestinal tract. More severe allergic reactions may be termed systemic and life-threatening from airway obstruction and circulatory collapse. 2. A 55-year-old previously healthy man has developed progressive renal failure for the past 5 years along with back pain. Microscopic examination of a renal biopsy shows extensive glomerular and vascular deposition of pink amorphous material on H&E staining. This material demonstrates apple-green birefringence under polarized light after Congo red staining. Immunohistochemical staining of these deposits is positive for lambda light chains. Which of the following conditions is most likely to be present in this man? A. Rheumatoid arthritis B. Tuberculosis C. Systemic lupus erythematosus D. Multiple myeloma E. Alzheimer disease Answer: D. The light chains are elaborated by plasma cells. Light chains from a plasma cell abnormality contribute to the formation of AL amyloid, in his case affecting renal function. Not all patients with AL amyloid, however, have multiple myeloma, and conversely just a subset of myeloma patients develop amyloidosis. The back pain suggests vertebral bone involvement by multiple myeloma. 3. A 22-year-old woman has experienced episodes of myalgias, chest pain, and arthralgias for the past 3 years. On examination a friction rub is audible on chest auscultation and there is dullness to percussion at posterior lung bases. No joint deformities are noted. She has continued working at her job. She has a mild normocytic anemia. A chest x-ray shows bilateral pleural effusions. Which of the following laboratory screening tests is most appropriate to begin the workup for her condition? A. CD4 lymphocyte count B. Blood culture C. Antinuclear antibody test D. Sedimentation rate E. Creatine phosphokinase Answer: C. These non-specific findings put together suggest possible autoimmune disease. An ANA is a good way to begin the workup, then more specific tests can be ordered. Antigen-antibody complexes of many autoimmune diseases can precipitate in a variety of locations, typically trapped in basement membranes in sites such as skin, synovium, pleura, pericardium, and glomeruli. The complexes elicit an inflammatory reaction with exudates/transudates. 4. A male infant is born at term. No congenital anomalies are noted on examination. A year later he now has failure to thrive and has been getting one bacterial pneumonia after another with both Hemophilus influenzae and Streptococcus pneumoniae cultured from his sputum. Which of the following diseases is he most likely to have? A. DiGeorge syndrome B. Selective IgA deficiency C. Epstein-Barr virus (EBV) infection D. Acute leukemia E. X-linked agammaglobulinemia Answer: E. Recurrent bacterial infections suggest a lack of B-cell immune function with lack of gamma globulin production. Once protective maternal antibodies are gone, the disease is manifested more severely. 5. A 52-year-old man with chronic kidney disease receives a renal allograft with matching by tissue typing for HLA-DR (Class II) antigens. He does not develop rejection as a complication. His serum creatinine remains in the normal range. Which of the following immunologic abnormalities has most likely been avoided by the tissue typing? A. Amyloidosis B. Cell lysis by CD8 lymphocytes C. Graft versus host disease D. CD4 lymphocyte activation E. Serum sickness Answer: D. Class II HLA antigens are involved in the process of CD4 lymphocyte activation. 6. A 5-year-old boy and his 4-year-old brother have had recurrent pneumonia, meningoencephalitis, sinusitis, otitis, and diarrhea since infancy. Bacterial and viral agents have been implicated, as well as Pneumocystis, Giardia, and Cryptosporidium. Laboratory studies show serum IgG 47 mg/dL, IgA 5 mg/dL, and IgM 671 mg/dL. Normal numbers of B and T cells are present. These children are most likely to have a mutation involving a gene encoding for which of the following? A. NADPH oxidase B. Wiskott-Aldrich syndrome protein C. Cytokine receptor common gamma chain D. CD40L E. Complement C1 inhibitor Answer: D. They have hyper-IgM syndrome, an X-linked disor