The expression of CD3, CD20, and CD21 in renal biopsy specimens was tested using immunohistochemical methods. Results. Serum CXCL13 levels were significantly higher in the LN group than those in the SLE group without LN and also in the type III and IV LN patients than in type V LN patients. The gene discussed is CR2; the disease is systemic lupus erythematosus.