Biomedical subjects
Publications and source records attributed to P Erb.
Explore the source record for details and available documents.
The in vitro induction and assay of bovine or porcine insulin specific T helper cells is described. Using a modified Marbrook-Diener culture system, helper cells were generated either by incubating purified T cells with insulin and macrophages or with supernatant obtained from insulin-incubated macrophages (GRF). The macrophage-T cell interaction required for helper cell induction was genetically restricted and the genes responsible were mapped to the left of the I-B subregion of the H-2 complex. The Ir gene control of the helper cell response to insulin was examined. It was found that the H-2d T cells became helper cells if incubated with bovine or porcine insulin and the appropriate macrophages. H-2b T cells only became helper cells if incubated with bovine but not with porcine insulin and macrophages. The Ir genes controlling that response were also mapped to the left of I-B. Studies to determine the cellular sites of Ir gene expression revealed that Ir genes function at the level of macrophages, although other sites have not been excluded.
The nature of the accessory cell type required for the in vitro induction of antigen-specific helper T (Th) cells to soluble antigen was determined. Two different sources of adherent accessory cells were investigated: peritoneal exudate cells (PEC) and macrophages derived from bone-marrow cells (BMM phi), which were cultured for 8 days in vitro with colony-stimulating factor. PEC and BMM phi were rosetted with EA-SRBC and separated by sedimentation into Fc gamma receptor-positive and negative fractions. Only the Fc gamma receptor-positive fraction was active in Th-cell induction. By means of the fluorescence-activated-cell sorter (FACS-II), PEC or BMM phi were separated either into phagocytic and nonphagocytic, or Ia-positive and Ia-negative cell populations. Only phagocytic and Ia-positive accessory cells induced antigen specific Th cells. In conclusion, the accessory cell is adherent, phagocytic, carries Fc gamma-receptors and Ia products, and thus expresses the most important characteristics of the macrophage lineage.
Explore the source record for details and available documents.
The genetic restriction in the T-cell-macrophage-like cell interaction in helper cell induction was investigated with allophenic and irradiation chimeras of various types. Using T cells from P leads to F1 chimeras, there was a restriction of cooperation with the parental haplotype accessory cells, unless the chimeric mice were repopulated with macrophages of the opposite haplotype before priming. T cells from primed or unprimed F1 leads to P chimeras only cooperated with recipient type accessory cells. These observations led to the hypothesis that there are two stages in the genesis of immunocompetence of T helper cells, one dependent on the thymus, and the other on peripheral macrophage-like cells. Purified T cells from P1 + P2 leads to F1 irradiation chimeras behaved in an unexpected manner in the unprimed state, preferring to cooperate with their own haplotype macrophages. This self preference was lost after antigen priming in vivo and was not noted in allophenic chimeras. This loss of self preference was restricted to the haplotypes represented in the chimeras, and did not extend to third party haplotypes. While these in vitro induced helper cells from chimeric mice show clear genetic restrictions at the T-cell macrophage-like cell interaction, there was no evidence for a matching T-B genetic restriction.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Two basic types of factors reacting with anti-I region (anti-Ia) antisera are compared, those derived from macrophage-like antigen presenting cells and others derived from T-lymphocytes, of either the suppressor or helper type. Despite the common property of reacting with anti-Ia antisera, the two sets of factors differ by many criteria. Macrophages, upon culture with antigen, release complexes of Ia antigen and a fragment of the original immunogen. This material is only produced by responder macrophages and thus appears to be a soluble Ir gene product. The genetic restriction of the T-macrophage interaction was investigated in chimeras, and it was found that the host environment as well as the donor genotype was of importance in determining restrictions, which were thus not really directed to "self." There was no evidence for intrinsic T-cell Ir genes, as nonresponder stem cells developed into responder T-cells in a (responder X nonresponder) F1 environment. However, these cells only responded in the presence of responder macrophages. Specific T-cell factors are different in nature. These all react with anti-Ia antisera, but the nature or function of the T-cell Ia is unknown. The basic structure involves a VARIAble region" responsible for antigen binding which, as it reacts with anti-idiotype antisera and anti-variable region framework antisera is an immunoglobulin variable region. There is also a "constant region," defined by its biological properties as well as by specific rabbit antisera. This two-region nature of specific factors is reminiscent of immunoglobulin structure and it is a reasonable hypothesis that the constant region is linked to the Ig cluster of genes.
Guinea pig peritoneal or alveolar macrophages were inoculated with Mycoplasma pneumoniae cells. Extracellular mycoplasms were killed by complement treatment, and the effect of macrophage action on the number of the remaining viable mycoplasmas was observed. The complement killing was to some extent inhibited by the presence of the macrophages, but the mechanism of this protection remains unknown. Opsonized mycoplasmas were ingested, and approximately 98% were killed within 4 h. The killing rate was somewhat lower than comparable data for bacteria, but lack of cell wall and high lipid content of the membrane apparently do not cause a significant delay in intracellular destruction.
The possibility that the antigen-presenting "macrophages" interacting with helper cells either directly or via the intermediary action of a soluble factor consisting of Ia antigen and a fragment of immunogen, termed GRG (genetically related factor), are a site of Ir gene action was investigated by using the synthetic polypeptide antigen (T,G)-A--L. It was found that T cells from (responder x nonresponder) F1 mice were stimulated by responder "macrophages" or GRF derived from these cells but not by the nonresponder macrophages of GRF from these cells. This suggests that the defect in helper cell induction in nonresponders is at the level of the presenting cell and that the macrophage factor GRF is a soluble Ir gene product. This conclusion was supported by the observation that there was normal presenting cell and GRF function in nonresponders, mouse strains such as CBA that yield helper cells and helper factor with (T,G)-A--L and have defects elsehwere.
In bone marrow cell (BMC) cultures supplemented with colony-stimulating factor (CSF), accessory cells develop that are capable of inducing specific helper T cells. These accessory cells become effective after 4 days in culture and can be found not only in the adherent but also in the nonadherent cell population. On the other hand, very few accessory cells with helper cell-inducing capacity are obtained in BMC cultures without CSF. The active BMC-derived cell type has been shown to carry Ia surface antigen, since pretreatment with anti-Ia serum and complement abolished the capacity of these cells to function like macrophages in helper T cell induction. Moreover, the appearance of functional accessory cells in these cultures coincided with the presence of Ia-bearing cells.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The properties of three I region associated immunoregulatory factors involved in cell interactions are described. These are antigen specific T helper factor, suppressor factor produced by metabolically active T cells and genetically restricted factor, which is produced by macrophages and is involved in T helper cell induction. The use of these factors to analyse cell interactions is discussed.
Explore the source record for details and available documents.
The generation of T helper cells in vitro requires macrophages or macrophage-derived factors such as genetically related macrophage factor (GRF) or nonspecific macrophage factor (NMF). However, there is a basic difference of T helper cell induction when using particulate antigens. The present study demonstrates that this difference is based on the activation of two different T cell subsets. GRF activates short-lived 'T1' cells which amplify the induction of T2 cells, which are the helper cell precursors. Thus, the genetic restriction of T helper cell induction seen with soluble antigen or GRF lies on the level of macrophage or GRF interaction with T1 cells. NMF (or macrophages) and particulate antigens directly activate the helper cell precursor (T2) indicating no requirement for T1-T2 cooperation. The direct activation of the helper cell precursor with particulate antigens does not require histocompatible macrophages or NMF from histocompatible macrophages. The present results may explain some of the discrepancies reported in the literature concerning the genetic requirements and specificity of T cell activation.
The evidence for the interaction of 2 subpopulations of T cells, short-lived cells sensitive to adult thymectomy (T1 cells), and long-lived recirculating cells, sensitive to the action of antilymphocyte serum (T2 cells) in the induction of helper cells is presented. This T-T interaction occurred across a cell-impermeable nucleopore membrane, indicating that it did not depend on cell contact, but was mediated by subcellular factors. There was no genetic restriction on this T-T interaction, if it was performed across a nucleopore membrane. The implications of these results on our concepts of the mechanism of help are discussed.
Explore the source record for details and available documents.