Immunomodulating Actions of RNA and Nucleotides on Murine LymphocytesIn Vitro

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Abstract
We have shown previously that yeast RNA significantly enhances in vitro antibody (Ab) production to sheep red blood cells (SRBC) in mice which can be partially reproduced by certain mononucleotides. In this study, mechanisms of this enhancing action by RNA and nucleotides were further explored in C57B/6 (B6) mice. Yeast RNA and certain mononucleotides augmented in vitro Ab production to SRBC and TNP-KLH (T dependent antigens) but not to TNP-LPS (a T independent antigen) and this action of RNA was abolished if T cells were depleted from spleen cell suspensions. RNA was most effective when supplemented on the first day of the culture for Ag priming. When RNA was supplemented after day 3 of the culture of Ag priming, no significant augmentation was observed. When spleen cells were cultured in the RNA supplemented medium, a frequency of L3T4+, CD5+, and Thy-1+ T helper cells increased significantly compared to controls cultured without RNA. However, yeast whole RNA did not appear to enhance IL-2 or IL-4 production. Therefore RNA and nucleotides may enhance in vitro Ab production at least partly by affecting T helper cells, perhaps by influencing the initial process of Ag priming.