Increased cytosol aminopeptidase and lactate dehydrogenase in serum originating from lymphocytes in measles and rubella infection

N. Sugaya, M. Nirasawa, K. Mitamura, Y. Takeuchi, M. Osano and T. Kanno
Department of Pediatrics, Nippon Kokan Hospital, Kanagawa, Japan.

We determined cytosol aminopeptidase (c-AP; EC 3.4.11.1) and lactate dehydrogenase (LDH) levels in serum; these enzymes are known to originate from lymphocytes in patients with measles and rubella. In patients with measles (n = 19), both enzyme levels increased markedly with the onset of rash: mean (+/- SD) c-AP was 269.7 +/- 103.5 U/L and LDH was 1149.5 +/- 255.2 U/L. In patients with rubella, activities of both enzymes increased mildly: c-AP (n = 18) was 81.6 +/- 24.4 U/L and LDH (n = 13) was 674.0 +/- 168.8 U/L. Increased c-AP and LDH levels in patients with measles and rubella presumably originate from the destruction of infected, activated lymphocytes, especially T lymphocytes.