L-carnitine modifies the humoral immune response in mice after in vitro orin vivo treatment

Although the role Of L-carnitine (L-Cn) as a cofactor in the oxidation of l ong-chain fatty acids has been well established, this agent has also been r ecognized to have an important role in the regulation of carbohydrate metab olism, and consequently, the maintenance of cell membrane structure and cel l viability. L-Cn has been reported to reduce the apoptotic levels of CD4() and CD8(+) cells. It has also been demonstrated to interfere with cells o f the monocytic lineage by regulating their ability to produce growth facto rs that ultimately affect both T and B lymphocytic subsets. Therefore, in t his study, we examined whether this agent affects the antigenic response of immune cells and determined the relative numbers of immune cells in the mu rine spleen after in vitro and in vivo treatment. The results showed that L -Cn reduces the relative numbers of CD8(+), CD4(+) and Ly5(+) cells. This o bservation was consistent in all systems studied including (a) in vitro ino culation of antigen (DNP-HSA) and L-Cn, (b) in vitro priming of spleen cell s treated with L-Cn in vivo, and (c) in vivo immunization and L-Cn administ ration. In all cases. the reduction of T lymphocytes correlated with the de creased production of interleukin-2. L-Cn, however, did not affect the prod uction of specific antibody, which indicates that the observed reduction of Ly5-positive cells is due to cell differentiation of B cells to plasma cel ls. (C) 2001 Elsevier Science B.V. All rights reserved.