Immunomagnetic separation of tumor necrosis factor alpha. I. Batch procedure for human temporomandibular fluid

A batch separation procedure has been developed for retrieval of tumor necrosis factor (TNF) alpha from the microliter volumes of fluid isolated from the human temporomandibular joint (TMJ). Paramagnetic beads coated with monoclonal antibodies for TNF were used. The beads, and bound TNF, were recovered from solution with the aid of a magnetic field. The amount of bead-bound TNF was quantified using an immuno-based assay developed in this laboratory called the cluster assay. The cluster assay was specific for TNF and linear up to 10 ng. Using these methods we found that TMJ fluid contained 0.2-4.2 ng per 100 microliters of fluid with a mean value of 1.9 ng and a standard deviation of 1.1 ng. This study demonstrates the utility of batch immunomagnetic separation for the concentration and purification of proteins, and the cluster assay for quantification of proteins from microliter volumes of body fluids.