Role of interleukin 2 on enhancement of concanavalin A-induced human peripheral blood lymphocyte proliferation by murine B cell mitogens

Widespread inosine-containing mRNA in lymphocytes regulated by ADAR1 in response to inflammation

Adenosine-to-inosine (A-to-I) RNA editing is a post-transcriptional modification of pre-mRNA catalysed by an RNA-specific adenosine deaminase (ADAR). A-to-I RNA editing has been previously reported in the pre-mRNAs of brain glutamate and serotonin receptors and in lung tissue during inflammation. Here we report that systemic inflammation markedly induces inosine-containing mRNA to approximately 5% of adenosine in total mRNA. Induction was the result of up-regulation of A-to-I RNA editing as both dsRNA editing activity and ADAR1 expression were increased in the spleen, thymus and peripheral lymphocytes from endotoxin-treated mice. Up-regulation of ADAR1 was confirmed in vitro in T lymphocytes and macrophages stimulated with a variety of inflammatory mediators including tumour necrosis factor-alpha and interferon-gamma. A late induction of RNA editing was detected in concanavalin A-activated splenocytes stimulated with interleukin-2 in vitro. Taken together, these data suggest that a large number of inosine-containing mRNAs are produced during acute inflammation via up-regulation of ADAR1-mediated RNA editing. These events may affect the inflammatory and immune response through modulation of protein production.

Antigen-specific proliferative response of peritoneal exudate lymphocytes primed with antigen and bacterial lipopolysaccharide: the roles of Ia+ accessory cells and IL-2

In vitro antigen-specific proliferation was investigated in a lymphocyte population that had been taken from the peritoneal exudate cells (PEC) of C3H/HeN mice (Iak) primed in vivo with both bacterial lipopolysaccharide (LPS) and horse red blood cells (HRBC) and had been purified by passage through a nylon fiber column (Nfc). The proliferative response of the Nfc-passed lymphocytes primed with HRBC and LPS [T(HRBC+LPS) cells] depended on the dose of antigen in the cultures, and the response was higher than that of cells prepared from mice primed with HRBC alone [T(HRBC) cells]. No response was seen in the cells prepared from the LPS-primed mice [T(LPS) cells] or normal mice [T(N) cells]. The response of the T(HRBC) cells was abolished by previous treatment of the cells with anti-Iak antibody and complement (C), whereas the response of the T(HRBC+LPS) cells was retained after the same treatment, indicating that the Ia- T(HRBC+LPS) cells can proliferate in response to antigen in spite of Ia+ accessory cell-depletion. Supernatants from the cultures of Ia- T(HRBC+LPS) cells in the presence of HRBC showed abundant IL-2 activity, while those of Ia- T(HRBC) cells did not. The IL-2 should be produced by the L3T4 cell population in T(HRBC+LPS) cells in response to antigen, since the previous treatment of the cells with anti-L3T4 antibody and C abrogated the production.(ABSTRACT TRUNCATED AT 250 WORDS)

Participation of interleukins in synergistic effect of Bu-WSA on concanavalin A-induced DNA synthesis in mouse splenic lymphocytes

Butanol-extracted water-soluble adjuvant (Bu-WSA) obtained from Bacterionema matruchotii was mitogenic to murine splenic B lymphocytes, but not T lymphocytes. When murine splenic cells were cultured in the presence of Bu-WSA and concanavalin A (Con A) together, [3H]thymidine uptake of the culture cells synergically increased. The mechanism of the synergy of Con A and Bu-WSA and the participation of interleukin (IL) 1 and 2 in the synergy were studied. The proliferation cells in the synergy were Lyt-1+23- lymphocytes. Ia-positive accessory cells were required for the response. When separated cell populations and Marbrook-type culture vessels were used, a mixed cell population of T lymphocytes and B lymphocytes or macrophages (M phi) produced some active factor(s) after co-stimulation by Con A and Bu-WSA, and the factors enhanced DNA synthesis of another Con A-activated T lymphocyte population. Supernatants obtained from the spleen cell cultures or the mixed cell cultures with T lymphocytes and M phi in the presence of Con A and Bu-WSA contained greater amounts of IL-1 and IL-2 than those from cultures containing Con A or Bu-WSA alone. An addition of exogenous IL-1 or IL-2 to spleen cell cultures with Con A resulted in a proliferative response like that obtained through co-stimulation by Con A and Bu-WSA. These results suggest that the synergistic effect of Con A and Bu-WSA on the proliferative response in murine splenic cells is sustained by the enhancement of production of these T-lymphocyte growth factors.