Conversion of human lymphocytes to antitumor immune reactivity by xenogeneic and allogeneic imune RNA detected by leukocyte-adherence inhibition tests

Summary Using leukocyte adherence inhibition (LAI) tests, we studied the activity of xenogeneic immune RNA (I-RNA) extracted from the spleen and lymph nodes of sheep after immunization with human breast carcinoma tissue or keyhole limpet hemocyanin (KLH) in inducing lymphocytes from normal healthy donors to mediate immune responses in vitro. Mononuclear cells isolated from venous blood of normal donors, depleted of monocytes and, in some experiments, separated into T cells and non-T cells, were incubated with and without anti-breast carcinoma I-RNA or anti-KLH I-RNA for 20 min at 37° C. Then, lymphocyte adherence was determined by a Coulter counter method in the presence of 3 M KCl extracts of breast carcinoma tissues, control tissue, or KLH. Following incubation with anti-breast carcinoma I-RNA, the adherence of lymphocytes from normal donors was found to be inhibited only in the presence of breast carcinoma extracts. Following incubation with anti-KLH I-RNA, lymphocyte adherence was inhibited only in the presence of KLH. The principal effector cells involved appeared to be T lymphocytes. I-RNA treatment with RNase, but not with DNase or pronase, completely abrogated the LAI responses. In a blind study utilizing coded samples of xenogeneic and allogeneic I-RNA of unknown origin, samples containing activity against breast cancer extracts were identified correctly by LAI.Abbreviations used: I-RNA, immune RNA; LAI, leukocyte adherence inhibition; KLH, Keyhole limpet hemocyanin; PBS, phosphate buffered saline; RNase, ribonuclease; DNase, deoxyribonuclease