Patients undergoing allogeneic haematopoietic stem cell transplantation (HSCT) are challenged by cytotoxic effects of the conditioning regimen, resulting in tissue damage, systemic inflammation and elevated metabolic demands for amino acids to regenerate damaged tissues, reconstitute hematopoietic cells, and establish antioxidant defenses. Few studies have addressed the role of plasma amino acid (PAA) levels during transplantation, and it remains unknown if amino acid deficiency can aggravate treatment-related morbidity.

We determined plasma levels of the 23 human amino acids in 80 HSCT patients (age 1.1-55.4 years) before conditioning and on day +7 and +21 post-transplant along with C-reactive protein (CRP) and Interleukin 6 (IL-6) levels on day +7.

Significant changes were observed in plasma concentrations of several human amino acids during HSCT. On day +7, several amino acids were inversely correlated with both CRP and IL-6, including glutamic acid, serine, alanine, glutamine, arginine, cysteine, glycine, histidine, lysine, tryptophan, threonine, taurine, proline, and methionine (r between -0.22 and -0.66, all p<0.05). Patients developing sinusoidal obstruction syndrome (SOS) had significantly lower total PAA levels compared to patients without SOS (2013 ng/l (1709-2318) vs 2706 ng/l (2261-3150), p=0.006) along with lower individual levels of glutamic acid, serine, arginine, glycine, lysine, valine, tryptophan, threonine, and proline (all p<0.05) on day +7. Patients with severe acute graft-versus-host disease had lower total PAA level (1922 ng/l (1738-2106) vs 2649 ng/l (2244-3055), p=0.014) and decreased levels of serine, glutamine, cysteine, glycine, lysine and threonine on day +7 (all p<0.05). These results indicate a relationship between low concentrations of certain amino acids and risk of treatment-related complications.