Question

Nine months later the patient contacted researchers in the Division of Clinical Immunology at Johns Hopkins University. The patient provided a blood sample, from which both serum and basophils were isolated, and a series of experiments were performed. First, basophils from the patient and from a random donor were treated with various concentrations of an antiserum specific for IgE ("anti-IgE") or jellyfish toxin (mixed tentacle nematocyst venom; "MTNV") and assayed for the release of histamine (FIG. 1). Then, basophils from a normal donor were treated with either normal donor serum or serum from the patient (either normal or heated to 56°C for 30 min) and then treated with various concentrations of MTNV and assayed for histamine release (FIG. 2). Question set 2: 3.) In Figure 1 an antibody against IgE induced histamine release from the patient's cells, as did MTNV. a. Explain why anti-IgE would do this. (2pts) b. A non-patient control (cells from an unaffected person) was not included in this experiment. Would you expect anti-IgE to trigger release of histamine from those cells as well? Why or why not? (2pts) 4.) In Figure 2 normal basophils treated with normal serum could not be stimulated by MTNV to release histamine, whereas those treated with serum from the patient could - but not if the serum was heated first. Explain these results. (4pts) 5.) These experiments were done in 1985. If you were to do similar experiments today, rather than measure histamine release you would assay basophils for surface expression of a protein called CD63. a. What is CD63? (2 pts) b. Why does CD63 appear on the surface of basophils and how would you use this to whether or not someone is allergic to a given substance (how would you do the test?). (2pts) 6.) The patient went to John Hopkins in hope of being desensitized to jellyfish venom. How would you desensitize a patient to a specific allergen such as she encountered? (5pts) FIG. 1. Histamine release from the patient's basophils by MTNV (?) and anti-IgE antibody (?). Normal control cells (?) did not respond to any concentration of MTNV. FIG. 2. Histamine release to MTNV after passive sensitization of normal basophils with the patient's plasma (?). No release occurred after sensitization with normal serum (?) or with the patient's plasma that had been heated to 56° C for 4 hr (?).

          Nine months later the patient contacted researchers in the Division of Clinical Immunology at Johns Hopkins University. The patient provided a blood sample, from which both serum and basophils were isolated, and a series of experiments were performed. First, basophils from the patient and from a random donor were treated with various concentrations of an antiserum specific for IgE ("anti-IgE") or jellyfish toxin (mixed tentacle nematocyst venom; "MTNV") and assayed for the release of histamine (FIG. 1). Then, basophils from a normal donor were treated with either normal donor serum or serum from the patient (either normal or heated to 56°C for 30 min) and then treated with various concentrations of MTNV and assayed for histamine release (FIG. 2).

Question set 2:

3.) In Figure 1 an antibody against IgE induced histamine release from the patient's cells, as did MTNV.
a. Explain why anti-IgE would do this. (2pts)
b. A non-patient control (cells from an unaffected person) was not included in this experiment. Would you expect anti-IgE to trigger release of histamine from those cells as well? Why or why not? (2pts)

4.) In Figure 2 normal basophils treated with normal serum could not be stimulated by MTNV to release histamine, whereas those treated with serum from the patient could - but not if the serum was heated first. Explain these results. (4pts)

5.) These experiments were done in 1985. If you were to do similar experiments today, rather than measure histamine release you would assay basophils for surface expression of a protein called CD63.
a. What is CD63? (2 pts)
b. Why does CD63 appear on the surface of basophils and how would you use this to whether or not someone is allergic to a given substance (how would you do the test?). (2pts)

6.) The patient went to John Hopkins in hope of being desensitized to jellyfish venom. How would you desensitize a patient to a specific allergen such as she encountered? (5pts)

FIG. 1. Histamine release from the patient's basophils by MTNV (?) and anti-IgE antibody (?). Normal control cells (?) did not respond to any concentration of MTNV.

FIG. 2. Histamine release to MTNV after passive sensitization of normal basophils with the patient's plasma (?). No release occurred after sensitization with normal serum (?) or with the patient's plasma that had been heated to 56° C for 4 hr (?).

Nine months later the patient contacted researchers in the Division of Clinical Immunology at Johns Hopkins University. The patient provided a blood sample, from which both serum and basophils were isolated, and a series of experiments were performed. First, basophils from the patient and from a random donor were treated with various concentrations of an antiserum specific for IgE ("anti-IgE") or jellyfish toxin (mixed tentacle nematocyst venom; "MTNV") and assayed for the release of histamine (FIG. 1). Then, basophils from a normal donor were treated with either normal donor serum or serum from the patient (either normal or heated to 56°C for 30 min) and then treated with various concentrations of MTNV and assayed for histamine release (FIG. 2).

Question set 2:

3.) In Figure 1 an antibody against IgE induced histamine release from the patient's cells, as did MTNV.
a. Explain why anti-IgE would do this. (2pts)
b. A non-patient control (cells from an unaffected person) was not included in this experiment. Would you expect anti-IgE to trigger release of histamine from those cells as well? Why or why not? (2pts)

4.) In Figure 2 normal basophils treated with normal serum could not be stimulated by MTNV to release histamine, whereas those treated with serum from the patient could - but not if the serum was heated first. Explain these results. (4pts)

5.) These experiments were done in 1985. If you were to do similar experiments today, rather than measure histamine release you would assay basophils for surface expression of a protein called CD63.
a. What is CD63? (2 pts)
b. Why does CD63 appear on the surface of basophils and how would you use this to whether or not someone is allergic to a given substance (how would you do the test?). (2pts)

6.) The patient went to John Hopkins in hope of being desensitized to jellyfish venom. How would you desensitize a patient to a specific allergen such as she encountered? (5pts)

FIG. 1. Histamine release from the patient's basophils by MTNV (?) and anti-IgE antibody (?). Normal control cells (?) did not respond to any concentration of MTNV.

FIG. 2. Histamine release to MTNV after passive sensitization of normal basophils with the patient's plasma (?). No release occurred after sensitization with normal serum (?) or with the patient's plasma that had been heated to 56° C for 4 hr (?).

Added by Victor T.

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