Correlation between rheumatoid factor and peripheral eosinophil count in chronic eosinophilic pneumonia.

The relationship between the blood level of rheumatoid factor (RF) and the peripheral blood eosinophil (Eo) count (white blood cellsx%Eo, Eo count) in a patient diagnosed with chronic eosinophilic pneumonia was evaluated from before the onset till resolution of the disease. RF levels correlated with Eo counts, and showed a strong correlation with the logarithmic value of the Eo counts (r=0.816). RF levels tended to become elevated earlier and decline later than Eo counts or abnormal X-ray shadows. We concluded that the RF level may reflect the activity of this disease. The mechanism of RF elevation in eosinophil-activated disorders needs to be clarified.