title: Interactions between B lymphocyte subpopulations. Augmentation of the responses of resting B lymphocytes by activated B lymphocytes.
abstract: Mouse B lymphocytes were fractionated from normal T lymphocyte-depleted spleen cell populations using discontinuous percoll gradients and were stimulated with rabbit F(ab')2 anti-mouse mu-specific antibodies (anti-mu) plus the supernatant of Con A-stimulated rat spleen cells (SN) as a source of lymphokines. The responses of small (mean volume 120 mu 3), dense (greater than 1.087 specific gravity), resting (least spontaneous thymidine incorporation) B lymphocytes were augmented by irradiated (4000 rad), larger (mean volume greater than 170 mu 3), less dense (less than 1.081 specific gravity), activated (greater spontaneous thymidine incorporation) B lymphocytes. Proliferation was augmented 2- to 4-fold and polyclonal antibody-forming cell responses three- to sixfold. Maximal augmentation of the responses of 5 X 10(4) resting B cells was obtained with 10(4) activated B cells. Augmenting activity was specific for activated B lymphocytes in that responses were not augmented by irradiated thymocytes, T lymphoblasts, macrophages, or additional supernatant. B lymphocytes activated in vitro by LPS or anti-mu also had augmenting activity. Augmentation of responses was maximal only when activated B lymphocytes were added simultaneously with anti-mu. The interaction between activated and resting B lymphocytes did not appear to be genetically restricted. Interestingly, the augmenting activity of activated B cells could be reconstituted by a combination of supernatant and cell membranes from these cells but not by either alone, suggesting that two components are required, one soluble and the other membrane-bound. Thus, a functional interaction has been demonstrated between B lymphocyte subpopulations which differ in their state of activation, and this interaction appears to involve a novel mechanism of action.
authors.affiliation: Immunology Branch, National Cancer Institute, Bethesda, MD 20892.
authors.forename: F
authors.initials: F
authors.lastname: Uher
authors.forename: H B
authors.initials: HB
authors.lastname: Dickler
mesh_terms: D000276:Adjuvants, Immunologic / Q000502:physiology; D000818:Animals; D001402:B-Lymphocytes / Q000145:classification* / Q000276:immunology / Q000502:physiology; D002450:Cell Communication; D002469:Cell Separation; D005260:Female; D007399:Interphase; D007700:Kinetics; D007958:Leukocyte Count; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA
chemical_list: D000276:Adjuvants, Immunologic