Antigen-binding specificity of isolated cell-surface immunoglobulin from thymus cells activated to histocompatibility antigens

Lactoperoxidase-catalyzed radioiodination of cell-surface proteins was used in the isolation of cell-surface immunoglobulin from thymus-derived thoracic duct lymphocytes activated to histocompatibility-2 antigens. Immunoglobulin was identified by specific precipitation with antiserum to mouse immunoglobulin. Polyacrylamide gel electrophoresis of reduced and alkylated precipitates showed that the immunoglobulin molecules possessed mu-type heavy chains and light chains. Cell-surface immunoglobulin isolated from thymus-derived cells activated to histocompatibility-2 antigens possessed binding specificity for the activating antigens.

The distribution of antibody and antibody-producing cells after immunization with xenogeneic cells

After intradermal injection of xenogeneic cells, antibody producing cells were demonstrated in the regional lymph nodes and peritoneal fluid as early as 5 days post-immunization. By 19 days antibody-producing cells were also found in the bone marrow, spleen and peripheral blood. They were not found in significant numbers in the thymus or non-regional lymph nodes. Antibody was demonstrable in the blood as early as 4 days post-immunization and reached maximum titre at 19 days. Both IgG and IgM were recovered from the thoracic duct lymph after intravenous injection. The significance of these findings is discussed in relation to the rejection of solid tumours and grafts.

Surface immunoglobulins on thymus and thymus-derived lymphoid cells

Lymphoid cells from thymus, thoracic duct lymph (TDL), and thoracic duct lymph in irradiated animals reconstituted with allogeneic thymus cells (TTDL) were labeled with radioiodinated anti-immunoglobulins using radioautographic techniques. Thymus and TTDL were labeled (14.4 and 37.0%, respectively) with anti-light chain protein after prolonged exposures (30-60 days). No labeling was observed on thymus and TTDL with anti-polyheavy chain globulin. In contrast 18.5-19.0% of TDL labeled on short exposure (6 days) with anti-polyheavy chain and anti-light chain materials. It is proposed that the difference between the labeling observed on short exposures versus long exposures can be related to the difference in surface density of immunoglobulins between nonthymus-derived (B) and thymus-derived (T) cells. The distribution of labeled cells in the thymus was preferentially among the larger cells (greater than 10 micro diameter). The TTDL population was mostly composed of a larger, blast-like population and the distribution of label was independent of size. As the thymus and TTDL preparations contain almost exclusively T cells, this represents a direct demonstration of surface immunoglobulin light chains on T lymphoid cells.

The sensitization of rats by allografts transplanted to alymphatic pedicles of skin

Pedicles of skin which lacked a lymphatic drainage were raised on the backs of rats in order to study the importance of afferent lymphatics in sensitization by skin allografts. Although allografts transplanted to the alymphatic pedicles enjoyed a prolonged survival, they contracted progressively from about 3 wk after transplantation and were reduced eventually to small scars. In contrast, autografts survived unchanged in size for the life-span of the pedicles which carried them. The slow contracture of the allografts was associated with sensitization of the host because test allografts applied orthotopically were destroyed with a second-set tempo. No regeneration of lymphatics from the long-standing pedicles could be demonstrated, and it was concluded that sensitization had occurred eventually through the blood, presumably by the process of peripheral sensitization. Allografts on skin pedicles could be destroyed rapidly by active or adoptive immunization, so it is probable that the level of sensitization to which they themselves gave rise was a low one. Although it is not disputed that afferent lymphatics are essential for the rapid destruction of skin allografts, it is clear that the absence of a lymphatic supply does not permanently exempt them from immunological attack in the rat.