Tolerance, Enhancement and the Regulation of Interactions Between T Cells, B Cells and Macrophages

Effector cells in delayed hypersensitivity and in vitro cytotoxicity were studied in lymph node cells from animals immunized with sheep erythrocytes (SRBC) in complete Freund's adjuvant. Delayed hypersensitivity response (DHR) was assayed by the increase in foot pad swelling after the intrafoot pad injection of immune cells plus antigen. Cell-mediated cytotoxicity against SRBC was assayed by a microcytotoxicity test with sheep fibroblasts as target cells. Effector cells were antigen specific, sensitive to anti-theta serum plus complement (C), and insensitive to anti-Ig serum plus C. A nonrosette-forming (non-RFC) small lymphocyte effector T cell and a rosette-forming medium lymphocyte effector T cell were isolated by velocity sedimentation. The small lymphocyte non-RFC required a longer time than the medium lymphocyte RFC effector cell to produce maximum activity. Buoyant density failed to distinguish medium lymphocyte effector cells in DHR and in vitro cytotoxicity.

Section: Discussionmentioning

confidence: 99%

Rosette-forming ability of thymus-derived lymphocytes in cell-mediated immunity. I. Delayed hypersensitivity and in vitro cytotoxicity.

Elliott¹,

Haskill²,

Axelrad³

1975

“…Such accessory factors may be antigen specific (1)(2)(3)(4) or nonspecific (1,2,(5)(6)(7) and may act as amplifiers (1)(2)(3)(4)(5)(6)(7) or suppressors (1,(8)(9)(10) of the immune response, thus illustrating the distinctive role of activated T cells in the modulation of B-cell responses to antigen (11,12) .…”

mentioning

confidence: 99%

Suppression of in vitro antibody synthesis by immunoglobulin-binding factor.

Gisler¹,

Fridman²

1975

119

Alloantigen-activated mouse T cells secrete a factor which binds to the Fc fragment of IgG and blocks complement (C) activation by IgG (immunoglobulin-binding factor, IBF). IBF was found to suppress the direct plaque-forming cell (PFC) response of mouse spleen cell cultures to sheep erythrocytes and to dinitrophenylated aminoethyldextran (T-independent antigen). Purification of IBF by affinity chromatography on IgG-coated Sepharose columns led to an increase of the suppressive capacity with IgG, IgM, or Fab2 from IgG) the factor responsible for inhibiting the PFC response could not be dissociated from that responsible for the inhibitory activity of IBF on C-dependent hemolysis. No effect was seen when cultures were pretreated for 6 h, or when IBF was added at 72 h. These data are compatible with the view that IBF is a soluable mediator of suppressor T cells which may interfere with terminal differentiation of antibody-forming cell precursors.

“…The failure to demonstrate rosette-forming helper cells does not imply that these cells do not recognize antigen specifically . Indeed, a high degree of specificity of helper cell activity has been demonstrated for some antigens (12,13). Although SRBC-primed helper cells do not form rosettes, carrier-primed helper cells have been reported to specifically bind carrier-coated erythrocytes (S .…”

Section: Resultsmentioning

confidence: 99%

Rosette-forming ability of thymus-derived lymphocytes in humoral and cell-mediated immunity. II. Helper cell activity.

Elliott¹,

Haskill²

1975

The technique of velocity sedimentation at unit gravity was used to determine the size and rosette-forming ability of helper cells in nonimmune and immune C57BL/6 mice. Helper T cells were assayed by the ability to cooperate with bone barrow (B) cells in the antibody response to sheep erythrocytes (SRBC) in vivo. 19S helper cells in nonimmune animals were nonrosette-forming small lymphocytes; after immunization with SRBC in complete Freund's adjuvant, 19S helper cells were nonrosette-forming medium lymphocytes. 7S helper cells in immune animals were small lymphocytes which did not form rosettes. No SRBC binding by helper cells was observed under the conditions of rosette formation used.