Platelets from cat and cattle with Chediak-Higashi disease were found completely devoid of
Ap4A as measured by high performance liquid chromatography. Using a very sensitive firefly biolumnescence method 6% of the normal content of
Ap4A was, however, found in platelets from sick animals. A content of Ap A of 1.90 +/- 0.11 X 10 M (means +/- SEM, n = 10) was found in whole normal human blood as measured by firefly bioluminescense method in
trichloroacetic acid extracts of the blood samples. This concentration corresponds to the contribution from the platelets, thus the contribution of
Ap4A from erythrocytes and the "buffy-coat" is negligible. Using the same method an
Ap4A contents in platelets of 0.063 and 0.021 nmol/mg of
protein compared to the normal content of 0.42 nmol/mg of
protein (1) was found in two patients with severe
myeloproliferative disorder calculated in this way on basis of platelet counts and on the assumption that 10(11) platelets contain 189 mg of
protein (2). Comparison of these figures with parallel HPLC analyses on
acid extracts of platelets isolated from the same patient were in agreement. The
storage pool deficiency of
adenine nucleotides in this disease found by others on basis of release experiments (3) can thus be diagnosed by rapid and simple measurements of
Ap4A in whole blood using the advantage of
Ap4A being a specific components stored in dense granules.