DIFFERENT PATTERN OF CYTOKINE PRODUCTION AND MESSENGER-RNA EXPRESSIONBY LYMPHOID AND NONLYMPHOID CELLS ISOLATED FROM HUMAN PALATINE TONSIL

To investigate the cytokines involved in the interaction between circu lating (B and T lymphocytes) and non-circulating (stromal cells) eleme nts present in lymphoid tissue, highly purified populations were isola ted from human tonsils and the cytokine production and mRNA expression (interleukin-1 alpha, -2, -4, -5, -6, -8, -10, leukocyte inhibitory f actor, granulocyte-macrophage colony-stimulating factor, and interfero n-gamma) were assessed both by immunoassay and reverse transcriptase p olymerase chain reaction under resting conditions and after activation with tumor necrosis factor-alpha. Under basal conditions most cytokin es were not detected, except for interleukin-8 which was produced by T lymphocytes and lymphoid cells. Activation by tumor necrosis factor-a lpha-induced interleukin-8 production by B lymphocytes. Tonsillar T ly mphocytes expressed mRNA for interleukin-1 alpha, -8, -10, -4, leukocy te inhibitory factor, and interferon-gamma, only interleukin-4 was exp ressed by resting peripheral blood T lymphocytes. Tonsillar B lymphocy tes were mRNA positive for interleukin-1 alpha, -8, -10, leukocyte inh ibitory factor, and interferon-gamma; these were not expressed by peri pheral blood B lymphocytes. Stromal cells constitutively produce inter leukin-6 whose levels increased 5 times upon tumor necrosis factor-alp ha activation Granulocyte-macrophage colony-stimulating factor and int erleukin-8 were detected only after tumor necrosis factor-alpha activa tion. Only stromal cells constitutively express interleukin-6 and gran ulocyte-macrophage colony-stimulating factor and show a cytokine patte rn different from that described for other non-lymphoid cells, such as follicular dendritic cells. These data indicate that in the human ton sil population, lymphoid and non-lymphoid cells can be distinguished b y different patterns of cytokine expression.