This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
Raji cell assay are used to quantitate- 
Select and explain. 
A. Complement levels, B. Immune complexes, C. T- cells, D. IFN levels
B: Immune complexes
Answer: B: Immune complexes 
Explanation: A sensitivie and simple procedure for the detection and quantitation of soluble complement (C)- fixing immune complexes in sera of patients with various disease states has been developed by utilizing C receptors on Raji cells. These cells lack membrane-bound immunoglobulin but have receptors for IgG Fc, C3b, C3d, and possibly with other C proteins. Uptake experiments showed that both aggregated human gamma globulin (AHG) and 7S IgG bound to receptors for IgG Fc; however, AHG reacted with C bound to cells only receptors for C and this binding was much more efficient than IgG Fc receptors. published in journal of clinical investigations. >.