Long-term decrease of CD4+CD45RA+ T cells and impaired primary immune response after post-traumatic splenectomy

Area of Science:

• Immunology
• Cellular immunology

Background:

• Absence of the spleen (splenectomy) or hyposplenism increases infection risk, particularly from encapsulated bacteria.
• The impact of splenectomy on cell-mediated immunity, especially regarding T cell subsets, remains largely uncharacterized.

Purpose of the Study:

• To investigate the long-term effects of splenectomy on peripheral blood lymphocyte subpopulations in humans.
• To assess the functional consequences of these changes on cell-mediated immunity, focusing on primary immune responses.

Main Methods:

• Analysis of peripheral blood lymphocyte subpopulations (CD4+ T cells, CD4+CD45RA+, CD4+CD45RO+) in splenectomized adults (>4 years post-surgery) and healthy controls.
• Assessment of lymphoproliferative responses and IFN-gamma production to recall antigens.
• Evaluation of T-cell proliferation to keyhole limpet haemocyanin and in vivo antibody responses to hepatitis A vaccine.

Main Results:

• A significant long-term reduction in CD4+ T cells, specifically the CD4+CD45RA+ (naive) subset, was observed in splenectomized individuals.
• Lymphoproliferative responses and IFN-gamma production to recall antigens were comparable between groups.
• Impaired primary immune responsiveness was evident, indicated by reduced T-cell proliferation to new antigens and diminished antibody responses post-vaccination.

Conclusions:

• The spleen may play a crucial role in the generation, maintenance, or differentiation of naive T cells or their precursors.
• Splenectomy can lead to a functional deficit in primary immune responses, potentially increasing susceptibility to novel pathogens.