The role of thymocytes and bone marrow cells in defining the response to the dinitrophenyl hapten attached to positively and negatively charged synthetic polypeptide carriers. Cell fractionation over charged columns

Transport and retention of selected engineered nanoparticles by porous media in the presence of a biofilm

Column experiments were conducted to investigate the transport of aqueous C60 (aqu-nC60), fullerol, silver nanoparticles (NPs) coated with polyvinylpyrrolidone (Ag-PVP) and stabilized by citrate (Ag-CIT) in biofilm-laden porous media. Gram-negative Pseudomonas aeruginosa (PA) and Gram-positive Bacillus cereus (BC) biofilm-laden glass beads were selected to represent the bacterial interfaces NPs might encounter in the natural aquatic environment. The biomass distribution, extracellular polymeric substances (EPS) components, electrokinetic property, and hydrophobicity of these interfaces were characterized, and the hydrophobicity was found to correlate with the quantity of proteins in EPS. The retention of NPs on glass beads coated with bovine serum albumin (BSA) and alginate were also studied. Except for Ag-PVP, the affinity of NPs for porous medium, indicated by attachment efficiency α, increased in the presence of biofilms, BSA and alginate. For hydrophobic aqu-nC60, the larger the proteins/polysaccharides ratio, the larger the α, suggesting the hydrophobic interaction determines the attachment of aqu-nC60 to the collector surface. Uncharged PVP stabilized Ag-PVP by steric repulsion, and the attachment to glass beads was not enhanced by biofilm. The presence of divalent ion Ca(2+) significantly hydrophobized biofilm, BSA, and alginate-coated glass beads and further retarded the mobility of aqu-nC60, fullerol, and Ag-CIT; while Ag-PVP was again sterically stabilized.

A leukocyte adherence inhibition (LAI) assay of anti-tumor immunity in rats using selective radioimmunological assessment of adherence of T lymphocytes and monocytes

A new, highly sensitive micro-glass-tube leukocyte adherence inhibition (LAI) assay has been developed to detect anti-tumor sensitization in a rat colon carcinoma system. This technique requires fewer cells and smaller amounts of antigen preparations than the previous glass tube method. The microscopic enumeration of adherent cells is replaced by a cellular radioimmunoassay (CRIA) which utilizes antibodies binding to mononuclear cells (MNC) and 125I-labelled protein A. Antigen preparations were shown to be adsorbed to glass. Precoating of glass vials with fetal calf serum or antigen preparations was shown to cause a major increase in nonspecific LAI. The new LAI technique is designed to minimize such nonspecific LAI. By applying an anti-T-cell monoclonal antibody (McAb), an anti-Ig antiserum and an anti-monocyte (MC) antiserum it became possible to assess selectively the change of adherence of T cells, B cells and monocytes. The specificity of the assay was demonstrated with anti-T-cell and anti-MC reagents in criss-cross experiments using two defined antigens and different tissue extracts as test antigens. The LAI response of peripheral blood MNC was examined after the subcutaneous isografting of 1 X 10(7) X-irradiated DMH-W49 colon carcinoma cells. Six days after sensitization all the rats showed an LAI response detectable with anti-T-cell and anti-MC reagents, which gave considerably higher LAI indices than anti-MNC antiserum. After the subcutaneous isografting of 1 X 10(5) viable DMH-W49 cells, 12 of 24 rats (50%) showed an LAI response detectable with the anti-MNC antiserum during a 3-week follow-up period. On the other hand, an LAI response was detected in all the 14 tumor-inoculated rats tested when the adherence of T lymphocytes and monocytes was assessed selectively.

Expression of an idiotype (Id-460) during in vivo anti-dinitrophenyl antibody responses. II. Transient idiotypic dominance

After immunization of mice with 2,4-dinitrophenyl-ovalbumin (DNP-OVA), it was shown previously that strains having Igh-Va genes and able to express light chains of the Vk1 group produce high levels of anti-DNP antibody bearing an idiotype (Id-460) associated with the combining site of the BALB/c DNP-binding myeloma protein MOPC 460. Expression of Id-460 in serum is transient; Id-460 levels peak early in the response and are regulated independently of total anti-DNP antibody. In this paper, the transient dominance of Id-460 expression has been confirmed at the cellular level by inhibition of splenic anti-DNP plaque-forming cells (PFC) with rabbit anti-Id-460 antiserum. Id-460+ PFC can account for 52-91% of anti-DNP PFC early after secondary challenge with DNP-OVA. Furthermore, Id-460 is represented at these high levels in IgM, IgG, and IgG1, and IgG2a, the three isotypes tested in the PFC assay, as well as in IgE, as tested by passive cutaneous anaphylaxis. Thus, there is no preferential association of Id-460 with a given isotype. We conclude from these studies that Id-460 is a dominant idiotype in the anti-DNP antibody response of BALB/c mice to DNP-OVA. This dominance is expressed transiently and is independent of isotype. A further conclusion from these studies is that regulation of isotype expression is independent of the regulation of idiotype expression in this system. We would suggest that regulation of Id-460 expression involves Ig-dependent helper T cells specific for Id-460 that induce Id-460+ B cells and also activate suppressor T cells, both events occurring via idiotype-anti-idiotype interactions.

Idiotypes, T-cell receptors, and T-B cooperation

T cells are responsible for virtually all the characteristics of the mammalian immune system except the production of serum antibody, in which they play a vital regulatory role. As such, they are central to our understanding of the immune system. T cells recognize cell-bound antigens with great precision, in association with self MHC antigens. They do this by means of antigen-specific receptors, whose antigen-combining sites are encoded in conventional VH genes. There is evidence that T cells carry at least two kinds of specific receptors, one for MHC antigens and one for non-MHC antigens. Both of these would bear VH-encoded and distinct idiotypic determinants. The process by which antigens associate with MHC-gene products on cell surfaces is poorly understood at present, and so is the process by which the two types of receptors communicate with each other. T cells are divisible into a number of subpopulations playing unique functional roles in the regulation of antibody responses. If one examines them further for other functions, even greater complexity emerges. Thus, all T cells may not have the same kind of receptor, which would not be surprising given the wide variety of functions they perform. Future work will undoubtedly focus on these important questions.

Evidence for an immunoglobulin-dependent antigen-specific helper T cell

Evidence from various systems suggests that thymus-derived lymphocytes can affect the quality of antibody responses by recognizing various portions of the immunoglobulin receptor of bone-marrow-derived thymus-independent lymphocytes. A model for this process is proposed involving two antigen-specific mature T helper cells, one of which also is specific for immunoglobulin determinants. These two cells act synergistically. Evidence from adoptive secondary antibody responses demonstrates that both cells are antigen-specific T cells and that the immunoglobulin-recognizing T helper cell is absent from experimentally agammaglobulinemic mice. This cell is termed an "immunoglobulin-dependent T cell" because its activation requires the presence of immunoglobulin.

Unprimed spleen cell populations recognize macrophage-bound antigen with opposite net electric charge

Previous studies have demonstrated an inverse charge relationship between the net electrical charge of antigen and the responding cells. In the present study we attempted to establish whether this phenomenon holds also for the primary recognition phase of cell-mediated immunity, when the involvement of the macrophage in presenting antigen is obligatory. Normal spleen cells were fractionated over negatively and positively charged columns. The fractionated cell populations, as well as the original cells, were sensitized in vitro on macrophage monolayers that were pulsed either with the basic encephalitogenic protein of myelin or with the acidic copolymer poly(Glu50,Tyr50). Cells eluted from glass bead columns(i.e., the more negative cells) could be sensitized only with the basic antigen, while cells eluted from poly(L-lysine)-glass bead columns (i.e., more positive cells) could be sensitized only to the acidic antigen. Thus, in delayed type hypersensitivity the inverse charge relationship prevails also for the primary immunological recognition of antigen bound to macrophages.

Separation of cells with different histocompatibility (H-2) antigens by passage through cellular immunoadsorbent columns

The anti-Ig column technique of Wigzell et al. (Scand. J. Immunol. 1972. 1:75) was adapted to the separation of mouse cells with different H-2 antigens. Fractionation was achieved by a two-step procedure: first the cells were treated with anti-H-2 sera, and thereafter passed over anti-mouse Ig columns. Antibody-coated cells were selectively retained in the anti-Ig column. The method could be applied to the separation of normal mouse lymphocytes or lymphoma cells with different H-2 antigen complexes and for the selective isolation of H-2 loss variants from a mouse carcinoma/fibroblast hybrid.

Specific separation of cytotoxic T lymphocytes on immunoadsorptive films

A method for the specific separation of cytotoxic T lymphocytes (CTL) on immunoadsorptive films is described. The films were prepared by polymerizing a mixture of gelatine and polyethyleneimine with glutaraldehyde on the bottom of plastic tissue culture flasks. By using an excess of glutaraldehyde unsaturated aldehyde groups on the film surface can react with other chemical groups predominantly with aliphatic amino groups. In this study detergent solubilized H-2 antigens were conjugated covalently to the films CTL, prepared by filtering spleen cells from alloimmunized mice through nylon wool columns, were incubated on immunoadsorptive films and the adsorbed cells were quantitatively recovered by mechanical detachment. The cells were functionally intact and tested in a microcytotoxicity assay using embryonic fibroblasts as target cells. Specificity adsorbed cells were enriched in specific cytotoxic cells up to 100 fold compared to the original fraction. Depending on the cell density per film area the non-adsorbed cells could be quantitatively depleted of CTL. The immunoadsorptive films are stabile at 37 degrees C and can be reused.

Inverse relationship between net electric charge on the antigen and that on the sensitized cell in cellular immune response: demonstration with basic encephalitogen of the brain

An inverse relationship exists between the net-electrical charge of immunogens and the antibodies elicited (1). The cellular basis of the net charge phenomenon has been established for both positively and negatively charged immunogens, by cell separation techniques over columns of opposite charge (7, 8). To establish whether this phenomenon can be extended to include cell-mediated immunity, the response to basic encephalitogenic protein (BE) which induces experimental allergic encephalomyelitis (EAE) was now investigated. Lymph node cells from sensitized strain 13 guinea pigs were fractionated over positively and negatively charged columns and compared to unfractionated cell populations in two assay systems: (a) in vitro response to BE in terms of lymphocyte transformation and (b) the passive transfer of EAE to unsensitized syngeneic recipients. The response was found to be confined to the fraction of cells eluted from glass bead columns, namely, the more negative cells. Cells eluted from poly-L-lysine-coated glass bead columns (i.e., positive cells) were devoid of the capacity to respond to this antigen either in vivo or in vitro. It was previously established that thymocytes rather than bone marrow cells account for the inverse charge phenomenon as assayed by T-helper-cell function in in vivo antibody production (8). We have now extended the inverse charge effect to include cell-mediated immune response of the delayed hypersensitivity type.