Elevated BAL fluid histamine levels and parenchymal pulmonary disease in rheumatoid arthritis.

To determine the amount of histamine in BAL fluid in subjects with RA and to ascertain if elevated histamine levels were associated with parameters of active pulmonary disease, we measured BAL fluid histamine levels in 31 subjects with RA and 36 normal subjects. The subjects with RA had a significantly greater mean BAL histamine level than the normal subjects, (313 +/- 154 pg/ml vs 18 +/- 8 pg/ml; p less than 0.05). When the subjects with RA were divided into three groups based on chest radiograms (1 = normal; 2 = pleural disease only; 3 = interstitial or nodular disease), we found that subjects in group 3 had significantly lower values for TLC and D. Subjects in group 3 also had higher percentages of BAL neutrophils and eosinophils and higher BAL histamine levels (group 1, 115 +/- 52 pg/ml; group 2, 30 +/- 30 pg/ml; and group 3, 1,182 +/- 709 pg of histamine per milliliter). Moreover, BAL histamine levels were negatively correlated with TLC (r = -0.46; p = 0.01) and FVC (r = -0.45; p = 0.01) and positively correlated with BAL neutrophils (r = 0.6; p = 0.0003) and BAL eosinophils (r = 0.89; p = 0.0001). These data suggest that the BAL histamine level may be a useful marker to determine the activity of pulmonary disease in RA.