Presence of nonesterified and acylcarnitine in human polymorphonuclear leukocytes and mononuclear cells.

We demonstrate the presence of nonesterified carnitine and acylcarnitine in leukocytes, but not in erythrocytes, from 16 healthy adults. After carefully separating the different kinds of blood cells we measured significant amounts of nonesterified carnitine and acylcarnitine in polymorphonuclear leukocytes (28.5 +/- 6.1 and 18.5 +/- 6.3 mumol/10(9) cells) and mononuclear cells (25.4 +/- 5.2 and 14.8 +/- 4.5 mumol/10(9) cells). We also measured nonesterified carnitine, long-chain acylcarnitine, and short-chain acylcarnitine in plasma after fractionation with perchloric acid and obtained the following values (mean +/- SD): 41.4 +/- 2.6, 3.9 +/- 1.2, and 6.0 +/- 1.6 mumol/L, respectively. The mean percentages of total carnitine (n = 6) in polymorphonuclear leukocytes, mononuclear cells, and plasma were approximately 62%, 27%, and 13% of whole-blood carnitine, respectively (mean recovery was 102%). The percentage of acylated carnitine was 37% in leukocytes, as compared with 19% in plasma.