Adoptive Therapy with T Cells/NK Cells

Lymphopenia in COVID-19: Therapeutic opportunities

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is uncontrollably spread all over the world. The host immune responses strongly try to confront it with all the potential cells and cytokines. With chronically condition of SARS-CoV-2, natural killer cells and T cells become exhausted and decreasing their count leads to lymphopenia. Inability to eradicate the infected organ makes hyperinitiation of the immune system, which releases the excessive inflammatory cytokines to compensate the exhausted one as well as the low lymphocytes counts; it consequently leads to the cytokine storm syndrome. These mechanisms and the potential therapeutic targeting are discussed in this paper.

Emerging immunology of stem cell transplantation

OBJECTIVES

To review critical areas of recent advances in immunology related to hematopoietic stem cell transplantation (SCT) and developing science that hopefully will be translated into improvements in patient care.

DATA SOURCES

Review of literature and electronic data.

CONCLUSION

An overwhelming amount of diverse information related to the science of immunology and hematopoietic SCT is available. Hot topics of clinical focus appear to be in the area of donor selection and human leukocyte antigen testing, cellular functioning as it relates to immune modulation, immune reconstitution, and the source of stem cells.

IMPLICATIONS FOR NURSING PRACTICE

The concept of immunity introduced over 200 years ago has evolved into everyday language in hematopoietic SCT. Nurses are challenged to keep their knowledge current with recent advances and the integration of immunotherapy into traditional care.

Rapid immune recovery and graft-versus-host disease-like engraftment syndrome following adoptive transfer of Costimulated autologous T cells

PURPOSE

Previously, we showed that adoptive transfer of in vivo vaccine-primed and ex vivo (anti-CD3/anti-CD28) costimulated autologous T cells (ex-T) at day +12 after transplant increased CD4 and CD8 T-cell counts at day +42 and augmented vaccine-specific immune responses in patients with myeloma. Here, we investigated the safety and kinetics of T-cell recovery after infusing ex-T at day +2 after transplant.

EXPERIMENTAL DESIGN

In this phase I/II two-arm clinical trial, 50 patients with myeloma received autografts after high-dose melphalan followed by infusions of ex-T at day +2 after transplant. Patients also received pretransplant and posttransplant immunizations using a pneumococcal conjugate vaccine only (arm B; n = 24) or the pneumococcal conjugate vaccine plus an HLA-A2-restricted microltipeptide vaccine for HLA-A2(+) patients (arm A; n = 26).

RESULTS

The mean number of T cells infused was 4.26 x 10(10) (range, 1.59-5.0). At day 14 after transplant, the median CD3, CD4, and CD8 counts were 4,198, 1,545, and 2,858 cells/microL, respectively. Interleukin (IL)-6 and IL-15 levels increased early after transplant and IL-15 levels correlated significantly to day 14 T-cell counts. Robust vaccine-specific B- and T-cell responses were generated. T-cell infusions were well tolerated with no effect on hematopoietic recovery. Eight patients (16%) developed a T-cell "engraftment syndrome" characterized by diarrhea and fever that was clinically and histopathologically indistinguishable from grade 1 to 3 acute graft-versus-host disease (GVHD) of the gastrointestinal tract (seven patients) and/or grade 1 to 2 cutaneous GVHD (four patients).

CONCLUSIONS

Adoptive T-cell transfers achieve robust T-cell recovery early after transplant and induce moderate-to-severe autologous GVHD in a subset of patients.

Immune reconstitution and implications for immunotherapy following haematopoietic stem cell transplantation

Recovery of a fully functional immune system is a slow and often incomplete process following allogeneic stem cell transplantation. While innate immunity reconstitutes quickly, adaptive B- and especially T-cell lymphopoeisis may be compromised for years following transplantation. In large part, these immune system deficits are due to the decrease, or even absence, of thymopoiesis following transplantation. Thereby, T-cell reconstitution initially relies upon expansion of mature donor T cells; a proliferation driven by high cytokine levels and the presence of allo-reactive antigens. This peripheral mechanism of T-cell generation may have important clinical consequences. By expanding tumouricidal T cells, it may provide a venue to enhance T-cellular immunotherapy following transplantation. Alternatively, decreased thymic function may impair long-term anti-tumour immunity and increase the likelihood of graft-versus-host disease.

T cell immune reconstitution following lymphodepletion

T cell reconstitution following lymphopenia from chemotherapy or stem cell transplant is often slow and incompetent, contributing to the development of infectious diseases, relapse, and graft-versus-host disease. This is due to the fact that de novo T cell production is impaired following cytoreductive regimens. T cells can be generated from two pathways: (1) thymus derived through active thymopoiesis and (2) peripherally expanded clones through homeostatic proliferation. During recovery from lymphopenia, the thymic pathway is commonly compromised in adults and T cells rely upon peripheral expansion to restore T cell numbers. This homeostatic proliferation exploits the high cytokine levels following lymphopenia to rapidly generate T cells in the periphery. Moreover, this early peripheral expansion of T cells can also be driven by exogenous antigen. This results in loss of T cell repertoire diversity and may predispose to auto- or allo-immunity. Alternatively, the high homeostatic proliferation following lymphopenia may facilitate expansion of anti-tumor immunity. Murine and human studies have provided insight into the cytokine and cellular regulators of these two pathways of T cell generation and the disparate portraits of T cell immunity created through robust thymopoiesis or peripheral expansion following lymphopenia. This insight has permitted the manipulation of the immune system to maximize anti-tumor immunity through lymphopenia and led to an appreciation of mechanisms that underlie graft versus host disease.