Rough-Form Lipopolysaccharide Increases Apoptosis in Human CD4+ and CD8+ T Lymphocytes

• Published in: Scandinavian journal of immunology Vol. 75; no. 2; pp. 193 - 202
• Main Authors: Nielsen, J. S., Larsson, A., Ledet, T., Turina, M., Tønnesen, E., Krog, J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-02-2012
• Subjects: Animal models; Annexin A5; Annexin V; Antigens, CD - metabolism; Apoptosis; Apoptosis - drug effects; Apoptosis - immunology; B-Lymphocytes - cytology; B-Lymphocytes - drug effects; B-Lymphocytes - immunology; Caspase 3 - metabolism; Caspase-3; CD4 antigen; CD4-Positive T-Lymphocytes - cytology; CD4-Positive T-Lymphocytes - drug effects; CD4-Positive T-Lymphocytes - immunology; CD8 antigen; CD8-Positive T-Lymphocytes - cytology; CD8-Positive T-Lymphocytes - drug effects; CD8-Positive T-Lymphocytes - immunology; Cell Separation; Clinical trials; Dactinomycin - analogs & derivatives; Endotoxemia; Flow Cytometry; Gene Expression; Humans; Immunophenotyping; Immunosuppression; Infection; Killer Cells, Natural - cytology; Killer Cells, Natural - drug effects; Killer Cells, Natural - immunology; Lipopolysaccharides; Lipopolysaccharides - chemistry; Lipopolysaccharides - pharmacology; Lymphocytes B; Lymphocytes T; Male; Natural killer cells; Peripheral blood mononuclear cells; Primary Cell Culture; Propidium; propidium iodide; Sepsis; Young Adult
• ISSN: 0300-9475; 1365-3083; 1365-3083
• DOI: 10.1111/j.1365-3083.2011.02613.x

Immunosuppression induced by lymphocyte apoptosis is considered an important factor in the pathogenesis of sepsis and has been demonstrated in both animal models of lipopolysaccharide (LPS)‐induced endotoxemia and septic patients. As rough‐form LPS (R‐LPS) has recently been shown to elicit a stronger immunological response than regular smooth‐form LPS (S‐LPS), we aimed to assess the apoptosis‐inducing capabilities of R‐LPS in different subsets of lymphocytes (CD4+ T cells, CD8+ T cell, B cells and NK cells). Using multicolour flow cytometry on human peripheral blood mononuclear cells, we found that R‐LPS increased apoptosis in CD4+ and CD8+ T cells assessed by annexin V and propidium iodide (AV+PI−), compared with both S‐LPS‐stimulated and unstimulated cells. 7‐Amino‐actinomycin D and staining for intracellular active caspase‐3, which are considered later signs of apoptosis, did not reveal the same results. Both forms appeared to inhibit apoptosis in B cells, but no LPS‐form‐specific effect was seen on B or NK cells. Our results indicate that R‐LPS induces a stronger AV+PI−‐assessed apoptotic response in T cells than S‐LPS. Our findings emphasize the importance of T cell apoptosis in endotoxemia and advocates for control of LPS form in both endotoxemia research and clinical trials with Gram‐negative infections.