Interferon-gamma-increased adherence of lymphocytes to high endothelial venules

Recirculating lymphocytes specifically adhere to and migrate through endothelium lining high endothelial venules (HEV), using specific and non-specific receptor-ligand systems. Interferons (IFN) profoundly affect the traffic of lymphocytes. Therefore the effects of interferon-gamma (IFN-gamma) on lymphocytes with respect to their interaction with HEV endothelium in lymph nodes were studied using the frozen section assay. In addition the organ-specificity of T- and B-lymphocyte adherence to HEV was investigated. Lymphocytes from spleen and peripheral lymph nodes showed increased binding to HEV of up to 35% compared to control lymphocytes after in vivo administration of IFN-gamma. The specificity of their binding did not change in terms of T:B-cell ratios. Increased adherence was also found by preincubation of lymphocytes with IFN-gamma in The enhanced binding was not due to increased expression of Mel-14 homing receptors and LFA-1 molecules on T and B lymphocytes, as shown by fluorescence-activated cell sorter analysis and antibody-blocking studies in the frozen section assay. Apparently IFN-gamma induces an additional Mel-14-independent and LFA-1-independent adhesion mechanism on lymphocytes.