Carnitine in erythrocytes and leucocytes represents a small but essential part of the cellular carnitine pool. It was the objective of this study to document the changes of blood cell camitine concentrations in disease entities with an enhanced cellular metabolism during acute and chronic inflammation. The plasma, erythrocyte, lymphocyte, granulocyte and thrombocyte camitine concentrations were determined in 23 patients (11.0 +/- 8.8 years) with bacterial infections and nine patients (17.5 +/- 2.4 years) with Crohn disease and compared to 20 healthy controls (27.0 +/- 10.6 years). In patients with bacterial infections the granulocyte camitine concentrations (126.4 +/- 73.5 nmoles/10(6) cells) were higher (P <0.001) than in controls (37.9 +/- 22.8 nmoles/10(6) eels). In patients with Crohn disease the lymphocyte carnitine concentrations (169.4 +/- 108.2 nmoles/10(6) cells) were increased (P < 0.001) when compared to controls (48.1 +/- 18.3 nmoles/10(6) cells). The plasma carnitine concentrations were decreased (P < 0.05) in both patient groups, whereas they were increased (P < 0.05) in the patients' erythrocytes. The carnitine concentrations in thrombocytes did not differ significantly within the individual groups.