EFFECTS ON IMMUNE RESPONSE 99Figure 5.1. Relationship between magnitude of irradiation and plaque-forming capacity of
mice. SRBC, 4 x 108, were given 10 days after whole-body irradiation, and
assays for plaque-forming spleen cells were performed 4 days later. The
results are plotted relative to the plaque-forming response of control
(nonirradiated) mice. Adapted from Kennedy et al.3
In general, irradiation inhibits the immune response in a dose-dependent
fashion. This is illustrated in Figure 5.1, taken from a study by Kennedy et
al.3 Mice were exposed to the indicated doses of radiation, injected with
antigen 10 days later, and then assayed for their capacity to produce anti
body. Similar results have been obtained in vitro,16 demonstrating that the
radiation-induced loss of functional activity is due to injury of the involved
cell types rather than a perturbation of the environment provided by the
host.
Whole body irradiation of mice also results in a dose-dependent loss of
substance among the various lymphoreticular tissues.9 As shown in Table
5.3 and Figure 5.2, this relationship is reflected in the recirculation pool.17
Table 5.3 shows the number of lymphocytes mobilizable by thoracic duct
cannulation as a function of radiation dose at various time intervals up to