Einat Zisman

Different roles of D-amino acids in immune phenomena.

Peptides and polypeptides either fully or partially built of D‐amino acids interest researchers because of their advantages over all L peptides and polypeptides. In exploiting these characteristics, one should realize that the resulting molecules are nonetheless not inert, but rather may induce a unique immune response, which is hardly cross‐reactive with the L‐enantiomer. Moreover, cross‐reaction between the L‐and the D‐sequences is limited also at the T cell level, probably due to different sterical conformations of the MHC‐antigen‐T cell receptor complexes formed. Polypeptides built exclusively of D‐amino acids lead to antibody formation only at a relatively low concentration, otherwise they provoke immunological paralysis. The specificity of the immune response toward peptides containing D‐amino acid residues is exquisite, and often D‐amino acids play a dominant role in defining the specificity. Polypeptides composed exclusively of D‐amino acids are thymus‐independent antigens. Nevertheless, it is possible to prepare against them highly specific T cell hybridomas. In future plans for synthetic vaccines against infectious or autoimmune diseases, the inclusion of D‐amino acids may be an advantage in terms of both specificity and efficacy, the latter because of longer persistence in an undigested form because they resist enzymatic degradation.—Sela, M., Zisman, E. Different roles of D‐amino acids in immune phenomena. FASEB J. 11, 449–456 (1997)

Autoantibodies to prostate specific antigen in patients with benign prostatic hyperplasia

PURPOSE We tested for a possible autoimmune process in benign prostatic hyperplasia (BPH). MATERIALS AND METHODS Titers of IgG antibodies to prostate specific antigen (PSA) were measured in the sera of 85 BPH patients, 20 controls and 17 chronic prostatitis patients by enzyme-linked immunosorbent assay. RESULTS The mean anti-PSA titers in the BPH group were significantly higher than in the controls and prostatitis group (p < 0.0005). Accordingly, 59% of BPH patients could be defined as responders to PSA compared to none among the controls (p < 0.0005). CONCLUSIONS Circulating autoantibodies to PSA were shown to exist in the sera of BPH patients. This observation suggests that autoimmune processes may have a role in BPH.

Altered Peptide Ligands of a Myasthenogenic Epitope as Modulators of Specific T‐Cell Responses

Myasthenia gravis (MG) is a T‐cell regulated autoimmune disease. A peptide representing a sequence of the human acetylcholine receptor α‐subunit (p195–212) was previously shown to stimulate proliferative responses of peripheral blood lymphocytes from MG patients and to be an immunodominant and myasthenogenic T‐cell epitope in SJL mice. The authors generated a panel of analogues of p195–212 that contain single amino acid substitutions. Three of the analogues (203PHE, 204GLY and 207ALA) triggered low to no proliferative responses of a p195–212‐specific T‐cell line designated TCSJL195–212. Two of these analogues were able to stimulate the line to produce interleukin‐2 (IL‐2) and IL‐4 (203PHE and 204GLY), whereas one analogue, 207ALA, did not stimulate the line to produce these cytokines. Binding assays revealed that the binding affinity of an altered peptide for a given major histocompatibility complex (MHC) molecule is not sufficient to determine whether it will be stimulatory or inhibitory to a native peptide‐specific T‐cell line. Two of the analogues, 204GLY and 207ALA, inhibited proliferative responses of cells of the TCSJL195–212 line when co‐cultured with p195–212 and syngeneic antigen presenting cells (APC). The two inhibitory analogues were also able to inhibit proliferative responses of the TCSJL195–212 line when APC were pre‐pulsed with p195–212, indicating that MHC blockade is not the only mechanism of action of these peptides. Moreover, both analogues inhibited the ability of p195–212 to prime lymph node cells for proliferative responses even when the analogues were administered in a soluble form. Thus the altered peptide ligands 207ALA and 204GLY can modulate T‐cell responses both in vitro and in vivo and may have therapeutic potential for the treatment of MG.

Binding of peptides of the human acetylcholine receptor α-subunit to HLA class II of patients with myasthenia gravis

MG is an autoimmune disease in which T cells specific to T-cell epitopes of the human acetylcholine receptor play a role. We have identified two peptides, p195-212 and p259-271, of the human acetylcholine receptor alpha-subunit, to which PBLs of MG patients responded by proliferation. Nevertheless, proliferation assays are relatively complicated to perform and might be affected by medications taken by the patients. Therefore, we tested the possibility of using a different assay to determine recognition of these peptides by MG patients. Thus, we performed a direct binding assay using biotinylated peptides and APCs from peripheral blood of MG patients and healthy controls. With this assay we detected the binding of the two peptides to the surface of intact APCs of both MG patients and control donors. Moreover, the presentation of peptide p259-271 by individuals with MG was significantly higher than that observed in healthy subjects. The peptides were specifically bound to HLA class II determinants on the APCs, as shown by inhibition with antibodies to the HLA class II haplotypes of the individuals investigated. Moreover, the binding of these peptides was in correlation with their ability to induce specific proliferative responses of peripheral blood T cells of these patients. The ability to screen for potentially pathogenic epitopes in each patient is of importance for the future design of specific inhibitory analogues that might be used to treat MG.

Production of colony-stimulating factor 1 by T cells: Possible involvement in their interaction with antigen-presenting cells

Colony-stimulating factor 1 (CSF-1) is required for the growth and differentiation of mononuclear phagocytes, and is also involved in modulating various activities in mature cells. We report herein that T-cell lines produce 4.6 and 1.5 kb mRNA species of CSF-1, and express the CSF-1 protein on their outer membranes, as determined by immunofluorescence staining with anti-CSF-1 antibodies. The CSF-1 protein is biologically active. Interested by the possible immunoregulatory function of CSF-1, we assessed its effect in an assay of antigen presentation to the T cell lines. We found that anti-CSF-1 antibodies inhibited T-cell stimulation. Moreover, soluble CSF-1 could not overcome this inhibition, but exerted a significant inhibitory activity on the interaction between T cells and antigen-presenting cells leading to T-cell activation and proliferation in vitro. Based on these observations we propose that T-cell CSF-1 may be involved in the interaction of these cells with CSF-1 receptor bearing antigen-presenting cells.

Prostate-Specific Antigen Induces Proliferation of Peripheral Blood Lymphocytes and Cytokine Secretion in Benign Prostate Hypertrophy Patients

Purpose: The etiology of benign prostatic hypertrophy (BPH) is still obscure. Data supporting an interaction connecting prostate hyperplasia and immune dysregulation is accumulating lately. The aim of the study was to assess the cellular immune responses to PSA by measuring the in vitro potential of PSA to induce proliferation and cytokine secretion in peripheral blood lymphocytes (PBLs) of BPH patients. Materials and Methods: PBLs were extracted from fresh blood of 36 BPH patients and 11 age-matched controls. The PBLs were incubated with PSA. Proliferation of the cultured PBLs was determined by thymidine incorporation. Secretion of cytokines to the culture medium was measured either by biological assay (IL-2) or by ELISA (IL-4, IL-10, IFNγ, TNFα). Results: Twelve of the 36 BPH patients responded to PSA, whereas none of the 11 controls responded (p = 0.04). The proliferative response of PBLs from BPH patients was significantly higher as compared to PBLs of controls (p = 0.03). The mean total prostate volume and the transition zone volume were 51% and 54% bigger, respectively, among the responders to PSA as compared to the nonresponders (p < 0.05), whereas the mean serum PSA level did not differ significantly. PBLs of BPH patients secreted significantly higher levels of TNFα, both spontaneously and in response to PSA, as compared to controls (p = 0.003). Conclusions: These findings show that PSA is able to induce proliferation of PBLs in vitro in BPH patients. Moreover, the higher spontaneous and PSA-induced secretion of TNFα in BPH patients may reflect a role for this proinflammatory cytokine in vivo. Based on these observations, we suggest that autoimmune dysregulation might have a role in BPH.

Ureterosigmoidostomy, Conduit and Continent Urinary Diversion

diversion. However, operative techniques are standardized today and the pouchrelated complication rates well known (2.8–4% early complications, 18–36.3% late complications). When a continent diversion cannot be performed, conduit diversion is required. The colonic conduit should be preferred in children and when life expectancy is long. With increasing life ex-pectancy of our patients, careful long-term follow-up (metabolic alterations, vitamins and secondary malignancies) after any type of urinary diversion become increasingly important and should be the subject of investigation.

T Cell Epitopes of Synthetic Antigens and of Antigens Related to Autoimmune Diseases

The initial observation that synthetic polypeptides may be immunogenic in experimental animals led to the use of synthetic antigens for the elucidation of the molecular basis of various immunological phenomena (1–4) and to the distinct realization of the determinant-specific genetic control of inmune response (5,6) and its correlation with the main Mstocompatibility locus of the species (7). In many of these studies use was made of the synthetic antigen “(T,G)-A--L”, a branched polyamino acid in which peptides of L-tyrosine and L-glutamic acid are attached to side chains of poly(DL-alanine), themselves attached to a backbone of poly(L-lysine) (8). The N-terminal peptides of tyrosine and glutamic acid were prepared by polymeric techniques, and thus both the detailed amino acid composition and their sequence varied from one polymeric side-chain to another.