LYMPHOCYTE SURFACE MARKER AND CYTOKINE EXPRESSION IN PERIPHERAL AND MUCOSAL LYMPH-NODES

Lymphocyte populations, adhesion molecule and cytokine expression were determined in lymph nodes draining peripheral (popliteal and prescapu lar) or mucosal (abomasal and jejunal) tissue sites using flow cytomet ry analysis, immunostaining and cytokine-specific reverse-transcriptio n-polymerase chain reaction (RT-PCR). Similar proportions of lymphocyt e subpopulations were present in all lymph nodes except for immunoglob ulin A(+) (IgA(+)) B cells which were only present in significant numb ers in the gastrointestinal lymph nodes. Peripheral lymph nodes contai ned a significantly higher number of CD4(+) cells expressing L-selecti n and beta 1-integrin than mucosal lymph nodes while the alpha 4-integ rin chain was expressed at similar levels in all lymph nodes. The peri pheral node adressin recognized by the MECA 79 monoclonal antibody (mA b) was mainly expressed on peripheral lymph node vessels. RT-PCR analy sis showed that interleukin (IL)-10 and IL-4 were preferentially induc ed in the gastrointestinal lymph nodes while IL-2 and interferon-gamma (IFN-gamma) were induced in all lymph nodes after polyclonal stimulat ion. These results indicate that there are substantial differences in the cell populations and microenvironments of lymph nodes draining muc osal and peripheral tissue sites in adult sheep.