Effects of hydrophobic amino acids and antibodies to nerve growth factor receptors on the development of splenic tissue culture from young and old rats.

The effects of hydrophobic L-amino acids alone and in the presence of monoclonal antibodies to nerve growth factor receptors NGFRp75 (apoptosis inductors) were studied on organotypic culture of splenic lymphoid tissue from young (3 months) and old (24 months) rats. Nine amino acids inhibited cell proliferation in splenic explants from young rats. This was paralleled by hyperexpression of p53 proapoptotic protein. Only two amino acids stimulated apoptosis in explants from old rats. The inhibitory effects on the development of splenic explants from young and old rats were abolished in the presence of antibodies to NGFRp75. Hence, the group of hydrophobic amino acids mediates the proapoptotic effect in the lymphoid tissue of old and young rats through nerve growth factor low affinity receptors.