Murphy et al. which performed on 89

Murphy et al. which performed on 89 women and 29 men over 65 years of age, it was showed that vit A supplementation of 800 μg/dl for 2 months could increase CD3+ T cell (25). The reasons for this difference might be the presence of immunologic factors in TB patients causing non significant alteration in blood CD3+ count or inadequate samples for detecting a significant difference in vit A- receiving group. Thus, it is recommended to use more samples.
Dawson et al. showed that the number of natural killer (NK) cells in mice with vit A deficiency were more than those with vit A supplementation (21). In a study conducted by Iwata et al. retinoic acid derivative was considered as Th2 system and plasma cell stimulator. This study was performed invitro on Th1/Th2 and showed that all-trans retinoic acid> 1nmol suppressed Th1 development while enhancing Th2 development.9-cis retinoic acid (9-cis RA) had also similar effect on all-trans form on development of the above mentioned systems (26).
As a conclusion, the immunologic response in TB patients is different comparing to non TB individuals. In some instances, our results are in contrary to other studies which may be due to a complex immunologic response, as the most important factor, to Mycobacterium tuberculosis itself, influencing expected results around vitamin A intensively.
Finally, regarding vit A influence on lymphocytic markers, further studies should be performed in order to use this vitamin for improving immune system.