Intraoperative cell salvage: The impact on immune cell numbers

BACKGROUND

Patient outcomes are influenced by many confounding factors peri-operatively, including the type of surgery, anaesthesia, transfusion, and immune competence. We have previously demonstrated (in-vitro) that compared to allogeneic blood transfusion (ABT), intraoperative cell salvage (ICS) improves immune competence. The peri-operative immune response is complex. Altered or impaired immune responses may predispose patients to develop adverse outcomes (i.e., post-operative wound infection, pneumonia, urinary tract infection etc.) Surgical patients may develop infection, even without the confirmed presence of a definite microbiological pathogen. With all these factors in mind it is important to consider changes in immune cell numbers (and sub-populations) and functional capacity during peri-operative transfusion.

METHODS

In this TRIMICS-Cell (Transfusion Related Immune Modulation and Intraoperative Cell Salvage-Cell numbers) study (n = 17, October 2018-November 2019) we prioritized and analysed peri-operative changes in the number and proportions of immune cell populations and sub-populations (B cells (CD20+), NK (natural killer) cells (CD56+), monocytes (CD14+), T cells (total CD3+ and sub-populations: T helper cells (CD4+), cytotoxic T cells (CD8+), effector T cells (CD4+ CD127+), activated effector T cells (CD4+ CD25+ CD127+) and regulatory T cells (CD4+ CD25+ CD127-)), plasmacytoid dendritic cells (pDC; Lineage-, HLA-DR+, CD11c-, CD123+), classical dendritic cell (cDC) (Lineage-, HLA-DR+, CD11c+), and cDC activation (Lineage-, HLA-DR+, CD11c+), co-stimulatory/adhesion molecules and pDC (CD9+, CD38+, CD80+, CD83+, CD86+, CD123+). Firstly we analysed the whole cohort of study patients and secondly according to the relevant transfusion modality (i.e., three study groups: those who received no transfusion, received ICS only (ICS), or both ICS and allogeneic packed red blood cells (pRBC) (ICS&RBC)), during major orthopaedic surgery.

RESULTS

For the whole study cohort (all patients), changes in immune cell populations were significant: leucocytes and specifically neutrophils increased post-operatively, returning towards pre-operative numbers by 48h post-operatively (48h), and lymphocytes reduced post-operatively returning to pre-operative numbers by 48h. When considering transfusion modalities, there were no significant peri-operative changes in the no transfusion group for all immune cell populations studied (cell numbers and proportions (%)). Significant changes in cell population numbers (i.e., leucocytes, neutrophils and lymphocytes) were identified in both transfused groups (ICS and ICS&RBC). Considering all patients, changes in immune cell sub-populations (NK cells, monocytes, B cells, T cells and DCs) and functional characteristics (e.g., co-stimulation markers, adhesion, activation, and regulation) were significant peri-operatively and when considering transfusion modalities. Interestingly DC numbers and functional capacity were specifically altered following ICS compared to ICS&RBC and pDCs were relatively preserved post-operatively following ICS.

CONCLUSION

A transient peri-operative alteration with recovery towards pre-operative numbers by 48h post-surgery was demonstrated for many immune cell populations and sub-populations throughout. Immune cell sub-populations and functional characteristics were similar peri-operatively in those who received no transfusion but changed significantly following ICS and ICS&RBC. Interesting changes that require future study are a post-operative monocyte increase in the ICS&RBC group, changes in cDC considering transfusion modalities, and possibly preserved pDC numbers post-operatively following ICS. Future studies to assess changes in immune cell sub-populations, especially during peri-operative transfusion, while considering post-operative adverse outcomes, is recommended.

Intraoperative Cell Salvage as an Alternative to Allogeneic (Donated) Blood Transfusion: A Prospective Observational Evaluation of the Immune Response Profile

Allogeneic blood transfusion (ABT) is associated with transfusion-related immune modulation (TRIM) and subsequent poorer patient outcomes including perioperative infection, multiple organ failure, and mortality. The precise mechanism(s) underlying TRIM remain largely unknown. During intraoperative cell salvage (ICS) a patient's own (autologous) blood is collected, anticoagulated, processed, and reinfused. One impediment to understanding the influence of the immune system on transfusion-related adverse outcomes has been the inability to characterize immune profile changes induced by blood transfusion, including ICS. Dendritic cells and monocytes play a central role in regulation of immune responses, and dysfunction may contribute to adverse outcomes. During a prospective observational study (n = 19), an in vitro model was used to assess dendritic cell and monocyte immune responses and the overall immune response following ABT or ICS exposure. Exposure to both ABT and ICS suppressed dendritic cell and monocyte function. This suppression was, however, significantly less marked following ICS. ICS presented an improved immune competence. This assessment of immune competence through the study of intracellular cytokine production, co-stimulatory and adhesion molecules expressed on dendritic cells and monocytes, and modulation of the overall leukocyte response may predict a reduction of adverse outcomes ( i.e., infection) following ICS.

Autologous intraoperative cell salvage ameliorates suppression of transfusion-related monocyte and dendritic cell inflammatory responses

ABO compatible allogeneic blood transfusion (ABT) is associated with transfusion-related immune modulation (TRIM) and poor patient outcomes including perioperative infection and myocardial infarction. Intraoperative cell salvage (ICS) enables collection, processing and reinfusion of autologous blood lost during surgery. We investigated whether immune suppression associated with ABT could be reduced by using ICS. Suitable orthopaedic patients were consented and recruited to the study (n=20, HREC/17/QRBW/685). 10mL anticoagulated blood (EDTA) was collected from the patient (pre-operatively) and from the ICS blood product. An established whole blood culture model was used to assess changes to monocyte and myeloid dendritic cell (mDC) inflammatory responses (intracellular cytokine staining for IL-6, IL-8, IL-10, IL-12, IL-1α, TNF-α, MIP-1α, MIP-1β, MCP-1, IP-10) following exposure of the patient’s pre-operative blood to ABO compatible allogenic blood (Blood Service, Kelvin Grove) or their ICS blood (P<0.05 ANOVA). Exposure to ABT significantly suppressed the inflammatory response of both mDC (IL-10, IL-12, IL-1α, IL-8, TNF-a, MIP-α, MIP-1β) and monocytes (IL-10, IL-6, IL-12, IL-1α, IL-8, IL-10, IL-12, TNF-α and MIP-1α). Compared to ABT, exposure to the patients’ own (ICS) blood improved mDC IL-8, IL-10, IL-12, TNF-α and MIP-1α production and monocyte IL-10 and MIP-1β production. We provide in vitro evidence that ICS may reduce ABT associated adverse outcomes associated with improved inflammatory response and immune competence post-transfusion.

Intraoperative cell salvage: A technology built upon the failures, fads and fashions of blood transfusion

Transfusion, as we know it today, developed into a very sophisticated treatment modality as a result of centuries of experimentation. Intraoperative cell salvage is a transfusion technique where autologous blood lost during surgery is reinfused. The success of this process relies on specialised equipment and techniques to collect, process, anticoagulate filter and reinfuse blood. Through a literature review, we collected information about the early origins of specific techniques relevant to intraoperative cell salvage: the ability to collect lost blood, to prevent collected blood from clotting, to remove debris through processing and other harmful aspects through filtering, the benefits of autologous blood transfusion, reinfusion and traditional concerns and contraindications. A culmination of knowledge specific to each of these techniques over centuries provides the background to the safe intraoperative cell salvage technique used today. In addition, we aimed to identify the reasons why specific equipment and techniques developed, why practice changed and what is still unknown. This article reviews relevant allogeneic transfusion and autotransfusion history, starting in Roman times, and includes landmark events through the centuries.