Rapid communication: effect of irradiation on lymphocyte proliferation and differentiation: potential of IL-6 in augmenting antibody responses in cultures of murine spleen cells.

Ionizing radiation induces both quantitative and qualitative changes in the lymphoid cells of both man and experimental animals, including inhibition of antibody responses. However, the cellular basis of this immunological lesion is not clear. In the present study, groups of mice were exposed to 2.0 Gy gamma-rays or sham irradiated, and 2 days later animals were killed and spleen cells were cultured with TNP-Ficoll and assayed for antibody responses. Results indicated a significant decrease in the number of anti-TNP, plaque-forming cells in cultures from the irradiated mice compared with cultures from the control. When lymphocytes were stimulated in vitro with anti-IgM or anti-CD3, there was a decreased proliferation in spleen cell cultures derived from the irradiated mice compared with those from the control. Since radiation treatment was found to deplete both T and B cells in equal proportions in spleen and an equal number of both control or treated cells were used in culture, the immunological abnormalities may have been due to intrinsic defects in irradiated cells. Addition of IL-6 to irradiated spleen cell cultures was able to augment anti-TNP, plaque-forming cell responses indicating the possibility that in the future this cytokine can be used in vivo to induce protection from infectious diseases in irradiated individuals.