Serum lactate dehydrogenase levels in adults and children with acquired immune deficiency syndrome (AIDS) and AIDS-related complex: possible indicator of B cell lymphoproliferation and disease activity. Effect of intravenous gammaglobulin on enzyme levels.

Twenty-seven of 33 patients with the acquired immune deficiency syndrome (AIDS) or AIDS-related complex (16 adults and 17 children) demonstrated significant elevation of serum lactate dehydrogenase activity, occurring in the isomorphic distribution. Serum lactate dehydrogenase activity was the highest in all nine patients with acute Pneumocystis carinii pneumonitis, in seven of whom extensive interstitial pulmonary infiltrates with lymphocytes and plasma cells were documented. Lactate dehydrogenase activity was also significantly elevated on a long-term basis in all 17 pediatric patients with non-Pneumocystis lymphoid interstitial pneumonitis. Clinical resolution of Pneumocystis carinii pneumonitis was associated with a decline in lactate dehydrogenase activity. Periodic intravenous gammaglobulin was more effective than conventional therapy (trimethoprim/sulfamethoxazole and pentamidine) in achieving clinical and immunologic improvement and reduction of serum lactate dehydrogenase activity in patients with Pneumocystis carinii pneumonitis. Intravenous gammaglobulin was also more effective in patients with AIDS and non-Pneumocystis carinii pneumonitis and lymphoid interstitial pneumonitis. Lactate dehydrogenase activity declined to normal, at least temporarily, in nine of 12 intravenous gammaglobulin-treated patients as compared with only two of 12 untreated patients. Six adult patients with AIDS or AIDS-related complex and no interstitial pneumonitis exhibited normal lactate dehydrogenase levels. These findings suggest that serum lactate dehydrogenase activity in patients with AIDS or AIDS-related complex may be a useful indicator of pulmonary interstitial inflammation. As such, it may be utilized to predict disease course and monitor response to intravenous gammaglobulin treatment.