Characteristics of a poly(LTyr,LGlu)-poly(DLAla)--poly(LLys)-specific helper factor derived from a T cell hybridoma

Immune modulation of biologic systems in renal somatic cells

The various theories discussed here suggest that somatic renal cells are susceptible to biologic modulation by the immune system independent of an inflammatory effect. (1) The mode of repression of type IV collagen synthesis by novel, soluble antigen-binding proteins, the down-regulation of class II MHC expression with interruption of antigen presentation to epithelia after selective gene regulation by antibody, and the diverse interactions of antibody with renal glomerular cells producing functional disturbances in endocytosis and permselectivity; (2) modification of surface-antigen composition; (3) alteration of matrix deposition, remodeling and composition; (4) biophysical perturbation of cytoskeletal and cell membrane components; (5) and lastly, alterations in cell adhesion through cell-surface alterations, all lend testimony to the richness of the signal transduction pathways in somatic cells. Although the preceding examples represent only a small fraction of those which may take place within the glomerular and tubular microenvironments, these paradigms may nevertheless serve as new models upon which one can consider the multitude of potential communications between disparate biologic systems that connect in complex organisms.

Effect of IFN-gamma on the immune response in vivo and on gene expression in vitro

T lymphocytes produce a variety of immunoregulatory molecules including gamma interferon (IFN-gamma) and antigen-specific suppressor and enhancer factors. During our studies of active substances obtained from cloned T-cell lines, we observed that certain fractions administered to mice resulted in enhancement of immune responses. Preliminary characterization of the substance suggested that it could be IFN-gamma and we therefore undertook a study of the action of IFN-gamma produced by recombinant DNA methodology on immune responses. We found that for several antigens, administration of IFN-gamma to mice leads to two- to five-fold enhancement of antibody formation provided that the IFN-gamma and antigen are administered together. The effect was dose dependent, giving a maximal response at 500-600 anti-viral units per mouse. Preliminary studies suggest that the macrophage may be the target of IFN-gamma action. Addition of IFN-gamma to cultures of a macrophage cell line leads to a greater than 10-fold increase in the level of RNA coding for I-region-encoded cell surface molecules.

Hapten reactive inducer T cells. II. Evidence that a secreted form of the T cell receptor induces antibody production

The biologic activity of molecules synthesized and secreted by hapten-specific inducer T cells was examined. After activation, a single inducer clone secretes both antigen-specific inducer peptides as well as nonspecific factors. The nonspecific factors augment the in vitro response of B cells to sheep erythrocytes (SRBC) and Type 2 T-independent antigens. The antigen-specific molecules (ABM) induce plaque-forming cell (PFC) responses in cultures containing ABM, B cells, and antigen that links the epitope recognized by ABM with the B cell epitope. Induction of B cells by ABM is limited to B cells expressing the same I-A allele as the source of the ABM and this reflects binding by ABM to I-A products on B lymphocytes. The data reported here strongly support the view that inducer cells can activate at least some B cells by secretion of a modified form of the T cell surface receptor.

T and B cells that recognize the same antigen do not transcribe similar heavy chain variable region gene segments

We have attempted to determine whether T cells and B cells that have the same antigenic specificity and whose receptors share idiotypic determinants in fact express similar VH gene segments. To do this, we have obtained and characterized a cDNA clone containing the entire coding sequence for the VH gene from a glutamic acid60/alanine30/tyrosine10 (GAT)-binding immunoglobulin that carries the CGAT idiotype. The GAT-VH clone was hybridized to Northern blots of GAT-specific T cell RNAs; there was no evidence of a T cell transcript that hybridized to the GAT-VH probe. The T cells analyzed included: (a) 10 GAT-binding suppressor T cell hybridomas, 6 of which secreted factors with CGAT idiotypic determinants, (b) one GAT-specific helper T cell hybridoma, and (c) two GAT-specific helper T cell lines grown in the absence of feeder cells. The detection limit of the Northern blot analysis was 1-2 copies of a particular mRNA species per cell for the hybridomas and 5-10 copies per cell for the T cell lines. Therefore, we conclude that T and B lymphocytes responding to GAT do not utilize similar VH gene segments. Furthermore, the presence of idiotypic determinants on T lymphocytes does not necessarily imply close structural similarity between T and B cell antigen receptors.

Human T cell hybridomas secreting immune interferon

Human T-cell hybridomas were established by hybridization of concanavalin A-stimulated human peripheral blood lymphocytes with a 6-thioguanine-resistant mutant cell line, designated SH9, derived by irradiation from a cloned human cutaneous T lymphoma line, Hut102-B2. High levels of interferon (IFN) were demonstrated in the supernatants of hybridoma L265 and its subclones. Whereas no IFN was detected in SH9 cell cultures, up to 1,330 units of IFN per ml were produced spontaneously by the hybrids. On induction with 12-omicron-tetradecanoylphorbol 13-acetate, IFN synthesis in hybridoma cultures was enhanced 8- to 16-fold. Neutralization with specific antisera and determination of antiviral activities in human and bovine cells showed that the IFN secreted by the hybridomas was immune IFN (IFN-gamma). Analysis of DNA content, karyotype, and cell surface phenotype, including T cell specific antigens and receptors, confirmed the T cell hybrid nature of L265 clones. No correlation was found in the hybridomas between IFN production and the expression of HTLV, a retrovirus released by Hut102-B2 and SH9 cells.