The rationale for use of PTX2 in IPF is the clinical evidence that circulating fibrocyte concentrations (which correlate with abundance of fibroblastic foci in IPF tissue) above 5% of total blood leukocytes predict lifespan in IPF at an average of 7.5 months, while fibrocyte levels below 5% are associated with lifespan of about 27 months.120. The gene discussed is APCS; the disease is idiopathic pulmonary fibrosis.