Regeneration of splenic tissue

Abstract

The ability of splenic tissue to regenerate after avascular transplantation at different target tissues is well documented but the capacity of splenic transplants to compensate the loss of spleen and the influence of the implantation site on the functional development of replants are still discussed contradictory, because little is known about specific functions of the transplants. Therefore, we investigated splenic implants in rats at different states of development and in different target tissues (intraomental and subcutaneous implantation site).Monoclonal antibodies directed against ϰ-light-chain (B-cells), B-type leucocyte common antigen (B-cells), CD5 (thymocytes and T-cells), CD4 (Thelper-cells), CD8 (Tsupp/cyt-cells), α/β heterodimer of the T-cell receptor (T-cell receptor bearing cells), ED-1 and ED-3 antigen (different functional macrophage subsets) and MHC class II molecules (la on B-cells and dendritic cells) were used to characterize splenic replants.The descriptive immunohistological characterization of both transplant groups revealed that within 40 days of regeneration all splenic compartments developed and cell classes and subsets were distributed similar to the spleen. Only slight differences concerning a reduced size of the T-cell area (including a decreased amount of CD8+ cells) and a delayed development of the immunoarchitecture in subcutaneous implants could be demonstrated. A quantitative immunohistological analysis of the red pulp (RP), periarteriolar lymphoid sheath (PALS), marginal zone (MZ) and follicles (F) elicited a number of subtle changes with respect to the cell density of transplant compartments. The alterations were restricted to an increase of B-cells and a decrease of Tsupp/cyt-cells in PALS, a reduction of B-cells as well as Thelper-cells in the marginal zone and a striking increase of la bearing cells in the follicles of both transplant groups. The results of a functional analysis using antigenic and allogenic stimulation of transplant cells confirmed the assumption that despite a spleen-like morphology and histology several alterations of the immunoarchitecture led to transplant-specific deficiencies on a subtle functional level.