Multiple myeloma (MM) is a haematological disorder of clonal malignant plasma cells, accounts for 1-2% of all human cancers.Multiple myeloma is characterised by slow proliferation of the tumour cells, mainly in the bone marrow,by production of large amounts of immunoglobulins and osteolytic lesions.Cytokines are involved in the growth and survival of these turnour cells.(A) Interleukin-6 (IL-6) is an important cytokine in the proliferation of different MM cells, via autocrine and/or paracrine regulation mechanisms.The multiple myeloma cells are classified into four groups depending on exogenous IL-6: (a) both proliferation and survival of the cells are dependent on IL-6, (b) only proliferation of the myeloma cells is affected by IL-6, (c) the cells are dependent on IL-6 only for survival, but not for proliferation, (d) the cells are independent of IL-6 both for survival and proliferation.Interleukin-10 (IL-10) is produced by MM cells spontaneously.It is an IL-6 related growth factor for MM cells.Tumor necrosis factor-alpha (TNF-alpha) is a growth factor for MM cells.(B) Elevated IL-6, IL-10 and TNF-alpha levels were detected in serum of patients having multiple myeloma, showing a relation to the clinical manifestation.(C) Several human MM cell lines were investigated in different experimental models.The cells were derived from blood, bone marrow, lymph node, pleura and ascites.The cultivated cells were treated with IL-6, IL-10, IL-6 receptor antagonist (IL-6RA), gp 130 antagonist (gp 130A).The following parameters were measured: Proliferation, Cell Cycle Phases, DNA-Synthesis, Expression of Membrane Receptors, Cytokines-Production, Levels of Cytokines and Soluble Receptors in the Supernatant, Viability, Apoptosis/Necrosis.Aim: (1) How do cytokines and antagonists affect these parameters, (2) The relationship between Interleukin-6,Interleukin-10 and Tumor necrosis factor-alpha.There are two important pathways against turnours: To inhibit the tumour cell proliferation (cytostatic effect) and/or to induce the death of the tumour cells (cytocidal effect).Cytocidal effect: apoptosis or necrosis.