IL6 and plasma cell myeloma: Together, the data support the notion that the very low concentrations of plasma IL‐6 measured under physiological conditions reflect an endocrine IL‐6 activity on target cells with more than 100 bioactive IL‐6 receptors (corresponding to 200 high‐affinity binding sites per cell), such as hepatocytes and activated T cells, and not least IL‐6 dependent malignant cells, for example, myeloma cells.26