Correction of equine severe combined immunodeficiency by bone marrow transplantation.

This study details how a horse with a severe combined immunodeficiency was treated successfully through a bone marrow transplant. The transplant led to an increase in immune responsiveness, with the horse showing effective antibody responses when immunized post-transplant.

Research Objectives and Methodology

• The primary goal of the research was to establish immunological responsiveness in a horse suffering from severe combined immunodeficiency. The method chosen to achieve this was a bone marrow transplant.
• The marrow donor was a histocompatible, full-sibling of the recipient horse, which reduces chances of rejection or complications related to the transplant.
• Histocompatibility was ascertained through a mixed-leukocyte-culture-nonreactive test, an important step to ensure that the recipient’s immune system does not attack the transplanted cells.

Transplantation and Post-Transplant Observations

• Within 14 days of the bone marrow transplant, there was significant improvement in the horse’s immune system. This was indicated by an increased total lymphocyte count, as well as increased numbers of T and B lymphocytes which are key components of the body’s immune response.
• 40 days post-transplantation, the circulating lymphocyte count had exceeded 1000 cells/microliter of blood, and by 170 days, both T and B lymphocyte numbers had reached normal values.
• The horse exhibited remarkable primary and secondary antibody responses post-transplant upon immunization with bacteriophage phi X 174.

Long-Term Post-Transplant Results

• Concentrations of immunoglobulins IgG and IgM (essential for the body’s immunity) stayed within the normal range even after plasma therapy stopped 156 days post-transplantation.
• More than 300 days following the transplant, the horse was healthy and growing normally.
• Crucially, there was no detectable evidence of graft-versus-host disease (a condition where donor’s cells attack recipients tissue) at any point during the post-transplant period, indicating the procedure was a success.

In summary, the study showcased a successful case of immunologic recovery in a horse afflicted with severe combined immunodeficiency using bone marrow transplantation. Demonstrating the potential of this treatment for horses with this immunodeficiency brings new hope for such cases in equine veterinary medicine.