23. Which type of hypersensitivity is mediated by IgE antibodies? a. Type I b. Type II c. Type III d. Type IV 24. Hemolytic disease of the newborn (erythoblastosis fealis) is a disease where a Rhesus-negative mother carrying a Rh-positive fetus may develop antibodies against this factor during birth. Which type of hypersensitivity is this? a. Type I b. Type II c. Type III d. Type IV 25. Rheumatoid arthritis and systemic lupus are what kind of hypersensitivity eactions? a. Type I b. Type II c. Type III d. Type IV

23. The correct answer is a. Type I. Type I hypersensitivity reactions are mediated by IgE antibodies. These reactions occur immediately after exposure to an allergen and are characterized by the release of histamine and other inflammatory mediators from mast cells and basophils.<br /><br />24. The correct answer is b. Type II. Hemolytic disease of the newborn (erythoblastosis fetalis) is a Type II hypersensitivity reaction. In this condition, the Rhesus-negative mother carrying a Rh-positive fetus may develop antibodies against the Rh factor during birth. These antibodies can cross the placenta and attack the fetal red blood cells, leading to hemolysis and anemia in the fetus.<br /><br />25. The correct answer is c. Type III. Rheumatoid arthritis and systemic lupus are examples of Type III hypersensitivity reactions. These reactions are also known as immune complex-mediated reactions. In these conditions, immune complexes (antigen-antibody complexes) are formed and deposited in various tissues, leading to inflammation and tissue damage.