Author Question: All of the following are true concerning hematopoietic stem cells except: a. They express both ... (Read 33 times)

Collmarie · **on:** Jun 25, 2018

All of the following are true concerning hematopoietic stem cells except:

a. They express both CD34 and CD117 (c-kit).
b. They lose some antigens as they mature.
c. They express both CD4 and CD34.
d. They gain lineage-specific antigens as they mature.

Question 2

A patient has a white cell count of 12.6 x 109/L, hematocrit of 28, and platelet count of 27 x 109/L.

Examination of a Wright-stained blood film reveals that almost all of the white cells in peripheral blood are blasts; the bone marrow is hypercellular with very little fat and is packed with blasts. Flow cytometry is performed on the peripheral blood cells, and a large cluster of cells is present that mark with CD20 and have monoclonal k light chains present on their surface. This patient has a:

a. Myeloid leukemia
b. Mature B-cell malignancy
c. Reactive B-cell hyperplasia
d. Mature T-cell malignancy

fffftttt · **Reply #1 on:** Jun 25, 2018

Answer to Question 1

ANS: C
CD4 is a marker of T cells, not hematopoietic stem cells (HSCs). HSCs express both CD34 and CD117 (c-kit). As they mature, some antigens are lost while lineage-specific antigens are gained.

Answer to Question 2

ANS: B
Mature B lymphocytes express CD20 and either k or l light chains on their surface. In a B-cell reactive process, a mixture of k and l light chain positivity will be observed. The expression of only one light chain on the surface of a population of B cells is called monoclonality and is indicative of a phenotypically mature B-cell malignancy.