180.The mechanism for lymphocyte circulation from the lymphoid com-
partment in the region marked with the asterisk to the blood involves
which of the following?
278 Anatomy, Histology, and Cell Biology
a. Homing receptors on lymphocytes that recognize vascular addressins on high
endothelial venule cells
b. Lymphocyte binding to endothelial integrins followed by passage through
endothelial cells lining the high endothelial postcapillary venules
c. Lymphocyte passage through the zonulae occludentes by diapedesis after dis-
solution of the junctions by proteolytic enzyme release
d. Lymphocyte passage from the efferent lymphatic vessel to the thoracic duct and
subsequently the venous system
e. Passage of lymphocytes through the discontinuous sinusoidal wall into the blood
181.Macrophages are directly involved in immune responses in which of
the following ways?
a. Production of IL-2
b. Presentation of antigen
c. Specific killing of tumor cells
d. Production of antibodies
e. Inactivation of helper T cells