Haematopoietic stem cell transplantation is a process that can be used in lymphoma therapy, especially in case of relapse or lack of response to first-line therapy. Transplantation consists in a very intense chemotherapy (conditioning) followed by re-infusion (simple transfusion) of a bag of haematopoietic stem cells, previously taken from the bone marrow (bone marrow transplantation) or, more frequently, from the blood (peripheral blood stem cell transplantation). We talk about autologous transplantation (auto transplantation) when the cells come from the patient and about allogeneic transplant (allotransplantation) when the donator is a different person (brother/sister or a genetically compatible stranger). In case of lymphoma the use of autologous transplantation is frequent whilst allogeneic transplant is used in selected cases generally after an unsuccessful autologous transplantation.
Peripheral stem cells are usually taken from peripheral blood after stimulation by granulocyte colony-stimulating factors. During such stimulation one can sometimes experience bone pain or a low temperature, these are normal side effects that nevertheless must be reported. The collection procedure is called apheresis; it can be carried out during a one day admission to hospital and consists in a blood draw from the arm vein or via a venous catheter. The blood is centrifuged in an equipment capable of separating and gathering together the only stem cells that can be frozen and then transferred back to the patient at the appropriate time. A variable period (10-15 days) follows the stem cells transfusion; this period is necessary to allow the transplanted stem cells to find their original location, proliferate and build up the normal marrow again. During this period, called aplasia, the immune defences are impaired and red blood cells or platelet transfusions are often necessary. After the high dose therapy, one of the expected side effects is mouth and/or intestinal mucosal inflammation (mucositis), which can arise during the low white count period.
The allogeneic transplant of haematopoietic stem cells consists in the re-infusion, to the patient, of cells from a healthy person after the so-called “conditioning” (a preparation involving intensive chemotherapy and/or radiotherapy). The preparation to the transplant also includes an immunosuppressive pre-transplant therapy to prevent rejection and a post-transplant therapy to prevent/monitor the reaction of the transplant versus host. The allogeneic transplant, unlike the autologous one, has also an immunological effect given by the ability of the healthy donator’s immune system to eliminate the receiver’s cancer cells which may potentially still be present in spite of the conditioning therapy. Such mechanism (positive effect of the allogenic transplant) is known as “Graft Versus Lymphoma”. The allogenic transplant primary complication is represented by an immune response, called “Graft versus Host Disease”, consisting in the eventuality that the donator’s lymphocytes attack the patient’s healthy cells (as these are alien to them).
The allogeneic transplant leads to the loss of “immunological memory” which includes the reduction of the antibody titre (IgG, IgA, IgM) that, in cases of recurrent infections, can be compensated for by the administration of immunoglobulin; the disappearing/reduction of vaccine antibodies (vaccines that must be repeated after the transplant); the reduction of lymphocytes T (CD4) which undergo a periodic dosage in order to be able to take into consideration the interruption of post-transplantation anti-infectious prophylaxis.
What should be done after an allogeneic transplant
The reduction of white cells increases the risk of contracting infections immediately after the transplant. The necessary lapse of time to allow the white cells and platelets to recover varies between 10 days and 3 weeks from the stem cells re-infusion. During this period the immune system will be particularly weak and, in order to prevent potential severe infections, or in order to immediately cure them with antibiotics, a period of hospitalisation is usually required. The hospitalisation for an allogeneic transplant usually lasts for at least four weeks. The recovery of normal general conditions usually requires an extra couple of weeks. Immunosuppression, particularly in the case of a graft versus host disease, can be long-lasting and further hospitalisation may be necessarry for the graft therapy and/or because of recurrent infections until the graft has completely regressed and the immune competence has completely recovered. This period can vary case by case and may also last for several months.
Due to the temporary immune system impairment, some behavioural and hygienical adjustments are necessary after the transplant:
- Be observant for any sign and symptom: promptly report to your doctor any symptom such as temperature, cough, shortness of breath, diarrhoea, constipation, skin redness, variations in weight;
- Take special hygiene precautions: wear a mask, avoid crowded places, avoid any contact with domestic animals (to avoid the risk of infections due to scratches, bites, contact with saliva or excrements), avoid sun exposure, avoid sharing towels with other people, whenever possible use a private toilet also at home, use protections when having sex, keep the house clean by using highly antiseptic products. The washing of the hands is fundamental especially during the 6 months following the transplant and throughout all immunosuppression period;
- Particular attention should be paid to nutrition: strictly stick to nutritional advice. Read carefully and abide by the rules on forbidden food and allowed food found in brochures and package leaflets provided upon dismissal. In case of doubt always consult the transplant centre staff on the occasion of the first outpatient examination.