RECEPTORS FOR AGGREGATED IgG ON MOUSE LYMPHOCYTES

Proliferative responses in mixed lymphocyte reactions (MLR) 1 are suppressed by a soluble factor released by alloantigen-activated splenic T cells (1, 2). We have established that such suppressive T-cell factors derived from one strain only suppress responses of strains histocompatible for regions of the H-2 complex between I-E and D (1, 2). H-2-dissimilar MLR responder cells are unaffected by active suppressor factors. The data suggest that a receptor specific for that factor and required for an active suppressive interaction is expressed by genetically homologous cells. H-2-dissimilar responder cells would lack the appropriate genetically determined receptor and upon exposure to suppressor factors would be unaffected. A similar "acceptor" site for primed helper T-cell factor has been postulated on B cells (3). Genes mapped in the I region control functional expression of the acceptor, as well as interacting factor molecules. Thus it may be through association of such molecules, either released or on cell membranes, with B-cell surface structures that appropriate cell interactions in antibody synthesis are achieved.Accordingly we have tested the ability of cells, used as MLR responder cells, to adsorb suppressor factor activity as an indication of a receptor for MLR suppressor molecules. The results suggest that such a receptor structure is dynamically expressed by a subpopulation of T lymphocytes only after a triggering antigenic or mitogenic signal. The receptor is not present or perhaps not functional on resting cells. H.2 control of the receptor molecule is suggested by the inability of activated H-2-dissimilar T cells to interact with and remove suppressor activity. Materials and MethodsMice. BALB/c and DBA/2 mice were obtained from the

Section: Discussionmentioning

confidence: 99%

Regulatory mechanisms in cell-mediated immune responses. IV. Expression of a receptor for mixed lymphocyte reaction suppressor factor on activated T lymphocytes.

Rich¹,

Rich²

1976

“…This indicates that the T lymphocytes do not need to be in an activated state to express the Fc receptor . Secondly, only 50-60% of the large "activated" T cells bear the Fc receptor (7)(8)(9), suggesting that activation does not always lead to acquisition of the Fc receptor. Finally, it was reported that KLH-activation of T lymphocytes resulted in a substantial increase in Fc+ T cells (8) .…”

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confidence: 99%

“…Graded numbers of these 1 wk KLH-primed T lymphocytes were then transferred into lethally irradiated syngeneic recipients along with 100 jig DNP-KLH and 5 x 10' anti-theta plus complement-treated spleen cells from (SJL x BALB)F, mice primed 1 mo previously with 100 Wg alum- Several groups have recently reported that the Fe receptor appears on T lymphocytes activated by exposure to KLH (8) or allogeneic cells (7,9). We have also found an increase in the number of Fc+ T cells as a result of allogeneic activation (unpublished observation).…”

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confidence: 99%

The Fc receptor on thymus-derived lymphocytes. I. Detection of a subpopulation of murine T lymphocytes bearing the Fc receptor.

Stout¹,

Herzenberg²

1975

135

Utilizing the fluorescence-activated cell sorter (FACS) and washed murine antibody-antigen complexes formed in antibody excess, we have demonstrated the presence of the Fc receptor on the surface of a distinct subpopulation of murine T lymphocytes. No differences in intensity of labeling with the complexes was observed when the Fc+ T lymphocytes were compared with Fc+ B lymphocytes. The majority of Fc+ T lymphocytes are small lymphocytes determined by light-scattering characteristics on the FACS. Separating Fc+ from Fc- T lymphocytes from spleens of mice primed 1 wk or 1 mo previously with keyhole limpet hemocyanin (KLH) revealed that the T cells capable of cooperating with DNP-KLH primed B cells to give an adoptive anti-DNP PFC response do not bear the Fc receptor.

“…To this mixture, 3-10 × l0 s cells in 0.3 ml were added. Incubation with intermittent agitation proceeded for 60 min at 4°C for macrophage-like cells and at 37°C for all other cells (7). The amount of radiolabeled IgG bound by the cells was determined by layering 0.2 ml of the reaction mixture on top of 1 ml cold fetal calf serum (FCS) in 1.5 ml conical polyethylene tubes and separating unbound from cell-associated IgG by centrifuging the cells through the FCS at 350 g for 8 min.…”

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confidence: 99%

Receptors for IgG: subclass specificity of receptors on different mouse cell types and the definition of two distinct receptors on a macrophage cell line.

Heusser¹,

Anderson²,

Grey³

1977

185

Fc receptors have been found on many different cells including B and T lymphocytes, macrophages, neutrophils, and K cells, as well as cells not involved in the immune system. Some cellular functions such as phagocytosis of IgG-coated particles (1, 2) and the antibody-dependent cell-mediated cytotoxicity reaction (3) can clearly be attributed to this surface activity. On the other hand, the functional significance of Fc receptors on other cells such as B and T lymphocytes has not as yet been elucidated. As part of our investigations of the possible function of Fc receptors, we have studied the specificity of receptors for immunoglobulins of different IgG subclasses, as well as the degree of polymerization of the immunoglobulin capable of binding to these receptors. For this purpose myeloma proteins of different IgG subclasses were chemically crosslinked by bis-diazotized benzidine (BDB).' Monomer IgG and IgG aggregates of comparable size, representative of the different subclasses, were examined for their capacity to bind to receptors on different established cell lines and normal cells. Our findings indicate that the binding of myeloma proteins is dependent both upon subclass and degree of polymerization. Furthermore, studies on a macrophage-like cell line (P388) strongly suggest the presence of at least two different receptors for IgG on this cell, one characterized by its reactivity with monomeric IgG2a and the other for its activity with aggregated IgG of all subclasses. Materials and MethodsMyeloma Proteins. The following IgG myeloma proteins were used in this study: MOPC-21 (IgG1), PC-5, and HOPC-1 (IgG2a), MOPC-141 (IgG2b), and J606 (IgGz). The myeloma proteins were isolated by starch block electrophoresis. Only the peak tubes of the myeloma protein-containing fractions were used. The myeloma proteins were cross-linked with BDB according to a modification of the method of Ishizaka (4) resulting in soluble complexes with a wide range of size.