The relationship between CD5+ and CD5- B cells, immunoglobulin-secreting cells (IgSC), and CD4 T cells in human immunodeficiency virus (HIV) infection

Lymphocyte populations and apoptosis of peripheral blood B and T lymphocytes in children with end stage renal disease

BACKGROUND

End stage renal disease (ESRD) is a worldwide devastating health problem due to its increased prevalence in the population and high association with several pathologic conditions including immunodeficiency, which makes a significant contribution to morbidity and mortality.

AIM

The present study aimed at analysis of T and B lymphocyte subpopulation and the detection of flowcytometric apoptosis markers on peripheral B and T lymphocytes in a cohort of children with ESRD.

SUBJECTS AND METHODS

A case-control study was conducted on 28 children with ESRD. In addition, 30 age and sex matched healthy children were included as a control group. We used Annexin V-FITC binding assay as a sensitive probe for identifying cells undergoing apoptosis.

RESULTS

Circulating neutrophils, T and B lymphocytes were lower in patient group. In addition, apoptotic B and T lymphocytes occurred more frequently in children with ESRD than in the control group.

CONCLUSION

Our finding of low numbers of circulating neutrophils, T and B lymphocytes, and increased portion of apoptotic B and T lymphocytes in children with ESRD, may emphasize the fact that these derangements are the main mechanisms responsible for the impairment of the immune system in ESRD children, also it adds to the fact that both cellular and humoral immunity affected in ESRD children. Finally, uremia and increased peripheral lymphocyte apoptosis were the major causes of lymphocyte populations' depletion in our ESRD patients.

Effect of end-stage renal disease on B-lymphocyte subpopulations, IL-7, BAFF and BAFF receptor expression

BACKGROUND

End-stage renal disease (ESRD) results in increased susceptibility to infections, impaired response to vaccination and diffuse B-cell lymphopenia. However, the precise nature and mechanism of ESRD-induced B-cell lymphopenia remains unclear. Therefore, we studied the distribution of major B-cell subsets, B-cell growth, differentiation and survival factors, IL-7 and BAFF, and their receptors in 21 haemodialysis patients and 21 controls.

METHODS

Innate B1 cells (CD19+, CD5+), conventional B2 cells (CD19+, CD5-), newly formed transitional B cells (CD19+, CD10+, CD27-), naïve B cells (CD19+, CD27-) and memory B cells (CD19+, CD27+) and BAFF receptor were quantified by flow cytometry. Plasma IL-7, BAFF, IL-6, TNF-alpha and IL-10 were measured by ELISA.

RESULTS

The ESRD group exhibited significant reductions of all B-cell subpopulations except for transitional B cells that were less severely affected. No significant difference was found in B-cell apoptosis between the ESRD and control groups. Moreover, plasma IL-7 and BAFF levels were elevated in ESRD patients, therefore excluding their deficiencies as a possible culprit. However, BAFF receptor expression was significantly reduced in transitional but not mature B cells in the ESRD group. Interestingly, B-cell activation with the TLR9 agonist resulted in significantly greater production of IL-6 and TNF alpha but not IL-10 in the ESRD group.

CONCLUSIONS

Thus, despite elevation of B-cell growth, differentiation and survival factors, ESRD patients exhibited diffuse reduction of B-cell subpopulations. This was associated with the down-regulation of BAFF receptor in transitional B cells. The latter can, in part, contribute to B-cell lymphopenia by promoting resistance to the biological actions of BAFF that is a potent B-cell differentiation and survival factor.

Single cell analysis of adenoid CD5+ B cells and their protective contributions to nasopharyngeal immunity

OBJECTIVES

CD5+ B cells are phenotypically and functionally distinct from the conventional (CD5-) B cells, and the function of CD5+ B cells in the upper respiratory tract remains unknown. A previous study showed that immunoglobulin A-producing cells in the adenoid play a protective role in the nasopharynx. In the present study, the contribution of adenoid CD5+ B cells to nasopharyngeal immunity at the single cell level was investigated.

STUDY DESIGN

In vitro laboratory study.

METHODS

Mononuclear cells were isolated from adenoids of children aged 1 to 12 years, and the frequency of CD5+ B cells was determined by flow cytometry. The numbers of cells producing immunoglobulin M, immunoglobulin G, and immunoglobulin A in sorted adenoid CD5+ B cells were determined by enzyme-linked immunospot assay. Further, to characterize adenoid CD5+ B cells, the expression of various surface molecules was analyzed by flow cytometry.

RESULTS

The results showed that adenoids of young children contain a relatively large number of CD5+ B cells, which have a greater capacity for antibody production than do CD5- B cells. CD5+ B cells also differed from CD5- B cells in the expression of interleukin receptors Il-4R, IL-5R, and IL-10R as well as CD27, B7-1, B7-2, Fas, and Bcl-2.

CONCLUSIONS

These findings suggest that adenoid CD5+ B cells contribute to protective immunity by forming a first line of defense in the upper respiratory tract of young children and that they are probably regulated in a manner that differs from that of CD5- B cells.