The effect of retinol (vitamin A) on human lymphocytes stimulated by phytohaemagglutinin. An ultrastructural study.

Retinol (Vitamin A) has been found to inhibit the stimulation of lymphocytes by certain mitogens. The ultrastructural morphology of phytohaemagglutinin-stimulated lymphocytes exposed to retinol 10 microgram/ml and 20 microgram/ml show that disaggregation of polyribosomes and formation of autophagic vacuoles ensue in the majority of the cells. Some of the lymphocyte clumps are unaffected and continue to show normal mitosis. The changes in the affected cell are similar to those seen in a cell undergoing hormonal involution and it is postulated that the effects of the retinol may be mediated by a retinol binding protein in the susceptible cells.