Immunoarchitecture and Specific Functions of Splenic Autotransplants at Different Implantation Sites

Abstract

The present study deals with the morphological and functional development of intraomentally and subcutaneously implanted splenic tissue. Spleens and splenic transplants from 138 Lewis rats were investigated with immunohistological, immunological and molecular biological methods at different times after operation (up to 200 days postoperatively). The analysis of the development revealed a nonsignificant reduction concerning the weight of subcutaneous replants and a nonsignificant decrease of the weight of female transplants of both groups at different phases after operation. The cell composition of cell suspensions from spleen and both transplant types showed a deficiency of T, B, MHC-L cells and a certain macrophage subset (ED-3⁺ cells) in transplants. In a quantitative immunohistological analysis of compartments (red pulp, periarteriolar lymphoid sheaths, marginal zone and follicles) the T cell reduction was related to the Tsupp/cyt cells and T cell receptor bearing cells in the periarteriolar lymphoid sheaths, whereas the density of T helper cells was normal. In addition, a different homing of K-light chain positive and leukocyte common antigen (B cell type)-positive B cells in follicles and marginal zone was detected. The amount of two macrophage subsets (ED-1⁺ and ED-2⁺ cells) was increased in the red pulp. Only minor differences in the immunoarchitecture of transplants at different implantation sites were measured. A functional analysis of spleen compared to both transplant groups elicited a B cell defect after LPS stimulation in subcutaneous transplants and a reduced allogeneic response of both transplant types but a normal proliferation of T cells after ConA stimulation and a correct IgM antibody response against sheep red blood cells. The in vivo mRNA expression and the expression kinetics of interferon-γ and granulocyte-macrophage colony-stimulating factor after antigen stimulation differed in both transplant groups with a remarkable permanent expression of both mediators in subcutaneous transplants. It can be summarized that the results clearly indicate a development of spleen-like immunoarchitecture of intraomental replants with subtle cellular, functional and molecular alterations. In contrast, despite a comparable development, some severe functional defects occurred in subcutaneous implants pointing out the important role of interactions between the regenerating splenic tissue and the target tissue on a functional and molecular level.

Autotransplantation of the spleen in the rat: donor leukocytes of the splenic fragment survive implantation to migrate and proliferate in the host

“…However, the size of splenic autotransplants, and their blood flow, is usually less than 30% of that of a normal spleen (Westermann et al 1988a, b). In addition, the relative size of the compartments and the protein content differ from a normal spleen (Westermann et al 1988a(Westermann et al , b, 1991Thalhammer et al 1992). Furthermore, splenic autotransplants cannot correct the disturbed migration patterns of lymphocyte subsets caused by splenectomy (Westermann et al 1989a;Willführ et al 1990;Blaschke et al 1995;Klonz et al 1996).…”

Operações laparoscópicas conservadoras do baço para tratar dor esplênica por isquemia

“…Essa operação é fundamentada na esplenose, em que fragmentos esplênicos implantam-se aleatoriamente em qualquer parte do corpo após trauma esplênico. Estudos experimentais indicaram que o melhor local para realizarem-se os implantes é o omento maior 4,5,6,7,8,28 . Essa escolha não se deve unicamente ao rico aporte sangüíneo dessa estrutura, mas também ao fato de sua drenagem venosa seguir para o fígado através do sistema porta, que é também a via natural de drenagem venosa do baço.…”

“…Essa escolha não se deve unicamente ao rico aporte sangüíneo dessa estrutura, mas também ao fato de sua drenagem venosa seguir para o fígado através do sistema porta, que é também a via natural de drenagem venosa do baço. Constatou-se em experimentos prévios que a boa função do baço depende dessa drenagem para o fígado 5,6,12,16,28 . B * FIGURA 3 -Controle imaginológico pós-operatório no segundo paciente submetido a esplenectomia subtotal por via laparoscópica.…”

“…No entanto, os auto-implantes ainda não foram adotados de maneira mais generalizada, apesar de comprovadas sua eficácia e facilidade técnica 4,6,7,8,28 . Mesmo assim, muitos médicos não acreditam que os fragmentos esplênicos implantados apresentem função adequada.…”

“…Nos casos em que não é possível preservar pelo menos parte do baço em posição ortotópica, existe a alternativa do transplante autógeno de tecido esplênico. Apesar de esse procedimento já ser conhecido desde o século XIX, há ainda poucos relatos de sua aplicação terapêutica 4,5,8,28 . Os estudos sobre o auto-implante esplênico iniciaram nesta linha de pesquisa em 1985.…”