Nuclear Medicine Technology and Other
Health Applications
Project Title: [ymphocytopoiesis and Transplantation Immunology
16.
Technical Progress in FY 1973: (Cont'd.)
RX-01-03-(d)
Routes of migration of lymphocytes from the calf thymus were shown
to be through the thymic lymphatics and veins.
The daily output of
lymphocytes from the thymus is 3-4 times greater than the number of small
Lymphocytes in the blood,
The question of magnitude of thymic cell migration to bovine
Peyer's patches is unresolved.
The animal studies were completed, but
the autoradiographic data analysis is not.
Most investigators studying
thymic lymphocytopoiesis and migration either label suspensions of thymic
cells or inject directly into the thymus, distorting its architecture.
Since studies following intra-arterial perfusion of the thymus with
tritiated thymidine showed a different distribution than the above
techniques, distribution of thymic cells after intravenous injectidn of
labeled thymic cell suspension was compared to that following intraarterial perfusion.
Following i.v. injection a greatly increased trapping
of thymic cells within the spleen was observed, suggesting that infusion
of thymic cell suspensions may provide quantitatively erroneous results.
Since transplanted allogeneic lymphocytes are believed responsible
for the development of graft vs host disease after bone marrow transplantation, the capability of isogeneic and allogeneic lymphocytes to
recirculate from blood to lymph was investigated using in vivo and
in vitro thymidine and cytidine labeling followed by transfusion or cross
circulation.
Preliminary results show that isogeneic lymphocytes are
capable of recirculating from blood to lymph whereas the allogeneic are
not endowed with this capacity. This work was planned for completion
in FY 1973 but due to Lack of personnel its completion is now planned for
FY 1974,
The turnover, in various lymphoid organs, of DNA labeled with
tritiated thymidine was compared to that of DNA labeled with I-125deoxyuridine using mice 1-8 days after birth.
Significant differences
in the exponential declines of these two isotopes indicate that in
addition to immigration, there is a significant cell death taking place
in the thymus during this period of development.
Similar analyses of
peripheral lymph nodes suggest that cell death and reutilization of
thymidine occurs in these organs. This is contrary to findings in lymph
nodes of young adult mice and further studies are underway utilizing
iso
d
lymph node perfusion to eliminate the effect of migration of
labelcells into and out of the Lymph node.
ke response of the lymphocytic system of the goats to ECIB was
studied during and up to two months after ECIB by observing changes in
the lymphocyte concentration and the "flash" labeling index of lymphocytes
in blood,
thoracic duct lymph,
thymus, prescapular lymph node, spleen,
(See Continuation Sheec)
1119230
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