CD8 dimer usage on alpha beta and gama delta T lymphocytes from equine lymphoid tissues.

The research involves studying the expression of the CD8 alpha or CD8 beta chains on lymphocytes from certain parts of the equine lymph system, using eight types of murine monoclonal antibodies. Results indicate that CD8 dimer usage by equine T lymphocytes is similar to other species. This finding can be leverage to further segregation of equine CD8+ T lymphocyte subsets from the lymphoid tissues to understand their role in protection against infections.

The Use of Monoclonal Antibodies

• Eight murine monoclonal antibodies (mAb) were used in this research. These antibodies can identify the equine CD8 alpha or CD8 beta chains expressed on lymphocytes in different areas of the lymph system.
• The use of these antibodies allowed researchers to determine the understanding of dimer usage in T lymphocytes, paving the way for potential advancements in combating viral and other infections.

CD8 Alpha and Beta Chains and Their Expression on Lymphocytes

• The CD8 alpha was identified as a 39 kDa protein and CD8 beta as a 32 kDa protein. Both chains were found on most of the CD8+ T lymphocytes present in the peripheral blood, spleen, thymus, mesenteric lymph nodes and even ileal intraepithelial lymphocytes (IEL).
• However, in every lymphoid compartment studied, there was still a certain percentage of lymphocytes that had only the CD8 alpha chain expression.

Differences in CD8 Expression and Co-Expression in T Lymphocytes

• The highest percentage of CD8 alpha alpha expressing T lymphocytes (up to 37.7%) was found in IELs.
• It was also found that purified T lymphocytes derived from the ileum co-expressed both CD8 alpha beta and the alpha beta T cell receptor (TCR). However, purified CD8+ T lymphocytes from the peripheral blood mononuclear cells (PBMC) had the ability to co-express either the alpha beta or gamma delta TCR, as per RT-PCR results.

Lysis of CD8 Expressing Population

• Utilizing the pooled anti-CD8 alpha mAb of the murine IgG2a isotype plus rabbit complement led to the lysis of the entire CD8 expressing population in the PBMC, which shows the power of these antibodies in potentially targeting specific lymphocyte populations.

Implication of the Findings

• Overall, the findings of this research indicate that CD8 dimer usage by equine T lymphocytes is similar to others species.
• This suggests that these monoclonal antibodies can be utilized further to differentiate distinct equine CD8+ T lymphocyte subsets from lymphoid tissues, and precisely define their function in potentially protecting against viral and other infections. This finding offers potential advancements in understanding and treating both equine and other infections in a number of species.