Transplantation of hands in humans has become an accepted therapeutic modality. A hand transplant is composed of various tissues of different degree of immunogenicity. In addition, skin contains own resident bacterial flora that may become virulent in the ischemic and rejecting graft. Discrimination between skin rejection and bacterial inflammation is difficult. The aim of our experimental study was to investigate the cellular reaction to skin bacteria and alloantigen in the regional lymph nodes draining skin and analyse the changes in cell phenotypes. The study was carried out on rats inoculated into hind-limb paw either with S. epidermidis or allogeneic peripheral blood mononuclear cells. An increase in lymph node weight and cell concentration was observed after bacterial infection. After stimulation with allogeneic cells, node mass increased significantly but its cell number rose much less. The percentage of lymph node W3/13 (leukocytes, T cells), W3/25 (CD4), OX8 (CD8), OX6 (class II), OX12 (B cells), ED1 (CD14), CD31 (lymphocytes), OX7 (stem cells), and OX62 (migrating dendritic) cells did not change in both groups compared to controls. There was a significant rise of the CD54 (ICAM 1) subset after bacterial infection and increase in percentage of OX8-cytotoxic and decrease of W3/25 (helper) subset after allogeneic stimulation. Lack of major differences between stimulated and control contralateral nodes may be explained by systemic reaction to the tested antigens affecting also nodes on the non-injected side. Comparison of the reaction of bacteria and alloantigen stimulated nodes revealed an increase in percentage of OX6, OX12, CD31, CD54, OX33 and OX62 after infection with S. epidermidis, whereas allostimulation brought about only rise in T (W3/13) cell population. Neither stimulation caused increase in expression of class II antigens on T cells. The obtained results demonstrate evident differences in type of response to bacteria and alloantigens. To what extent can bacterial stimulation enhance allogeneic reaction is now under study. Our data are helpful in understanding differences in the character and kinetics of reaction to both types of antigens and may taken into consideration when planning therapy in recipients of hand allografts, immunosuppressive drugs or antibiotics.

Keywords: Hand Transplantation, Bacteria, Lymph Nodes, allogeneic, Antigens