the action of vitamin a ( retinol ) and the synthetic retinoids , isotretinoin , etretinate , acitretin , and arotinoid-free acid have been studied on the lymphocyte proliferation induced by phytohemagglutinin ( pha ) , by the mixed lymphocyte reaction ( mlr ) , and the mixed epidermal cell-lymphocyte reaction ( meclr ) .
C0042839
vitamin a
C0035339
retinoids