Immune monitoring in humans after manipulation by B cell depletion and immunization
Year: 2007
Type: dissertation
Abstract: The overall goal of this thesis was to study the influence of\nimmunomodulatory drugs on the human immune system. The approach was\nbi-directional; ex vivo studies were performed after B cell depletion\nwith rituximab treatment in patients with SLE and RA, and an in vivo\nassay was established to study effects of drugs on immune responsiveness.\n\nTo study immunological consequences of B cell depletion by rituximab in\ntreatment resistant patients with SLE and RA we collected blood samples\nbefore and after treatment. Our analysis was focused on time points\nrelated to absence and return of B cells after depletion. In patients\nwith SLE, changes of cellular phenotypes were analyzed by flow cytometry\nand changes in antibody levels in serum by ELISA. We observed an increase\nof activated T cells as well as an increase of regulatory T cells after B\ncell depletion. There was a selective decrease of antibodies in serum.\nIgM and IgE decreased rapidly after B cells depletion as well as the\ndisease activity associated autoantibodies against dsDNA and C1q. BAFF\nand APRIL levels were measured by ELISA in serum of both SLE and RA\npatients. Levels of BAFF increased in all patients after rituximab\ntherapy. In patients with SLE, the levels of APRIL decreased after B cell\ndepletion, and in patients with RA we observed heterogeneous changes.\n\nTo set up an assay to measure individual immune responsiveness, we used\nimmunizations as a tool to trigger an immune response. Healthy volunteers\nwere immunized with four weeks interval with either influenza vaccine,\nthree or four times (n=11) or with tetanus toxoid four times (n=7). Blood\nsamples were collected before and at four occasions between days 4 to 10\nafter each immunization. Humoral immunity to the influenza vaccine and\ntetanus toxoid was measured by ELISPOT (circulating B cells) and ELISA\n(antibodies). Cellular reactivity to the influenza vaccine was measured\nby FASCIA (proliferation) and Bio-Plex suspension array system\n(cytokines). Comparing the response to influenza and tetanus, the first\nimmunization with influenza vaccine resulted in ten times more B cells\nsecreting antigen-specific antibodies compared to immunization with\ntetanus toxoid. The second and third influenza immunizations induced\ncomparable B cell immune responses, while there was a very low or no\nresponse to tetanus toxoid. Antibody titers and T cell responses only\nincreased significantly after the first immunization. Thus measuring B\ncell responses by ELISPOT to repeated immunizations with influenza\nvaccine provide a method to evaluate immune responsiveness. Tetanus\ntoxoid was not a suitable antigen trigger for such studies.\n\nIn conclusion, we observed an effect on both the humoral and the cellular\nimmune systems after rituximab-induced B cell depletion in patients with\nSLE. Further on, levels of BAFF increased after the therapy in patients\nwith SLE and RA, while APRIL decreased in SLE only. We have set up an\nassay in which reproducible immune responses can be measured after\nimmunization 2 and 3 with influenza vaccine. Such an assay allows us in\nthe future to estimate the influence of immunomodulatory drugs on the\nimmune responsiveness in single patients.
Source: Figshare
Author: Therese Vallerskog
Language: English
Subfield: Rheumatology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W1934301612