What are B-1 cells and their main differences from conventional B cells?

Conventional B-2 cells cooperate with T cells in the germinal center to provide high-affinity long lasting antibody responses (7). On the other hand, B-1 cells spontaneously secrete natural antibodies mainly against non-protein antigens in the absence of exogenous immunization.

Do B-1 cells express CD5?

Many B-1 B cells express the CD5 (Ly-1) molecule. Through secretion of broadly cross-reactive natural antibodies such as IgM (mainly), IgA and IgG3, these cells respond to TI antigens primarily in the peritoneal and pleural cavities as well as in mucosal tissues (Smith and Baumgarth, 2019).

What is the function of B-1 cells?

B1 cells are a sub-class of B cell lymphocytes that are involved in the humoral immune response. They are not part of the adaptive immune system, as they have no memory, but otherwise, B1 cells perform many of the same roles as other B cells: making antibodies against antigens and acting as antigen-presenting cells.

What are human B cells?

1 Introduction. B cells, also known as B lymphocytes, belong to the white blood cells. They secrete antibodies and are a part of the adaptive immune system. B cells also play a role as professional antigen-presenting cells (APCs) and secrete cytokines.

How many B cells do humans have?

Your body has up to 10 billion different B-cells. They’re too small to see with your eyes, but if you lined them all up, they’d be longer than 100 soccer fields. With so many different B-cells patrolling your body, you are ready to fight almost any invader.

How are B-1 cells activated?

B-1 cells express poly-reactive BCRs with cross-reactivity to self-antigens. Accidental activation by self-antigens is prevented by multiple mechanisms that keep B-1 cells in anergic state. Lyn, a major negative regulator of BCR signaling phosphorylates ITIMs on inhibitory receptors (CD5, Siglecs, etc.)

What activates B-1 cells?

Anatomical location of B-1 cells makes them prone to activation through microbial TLR ligands that might result in auto-antibody production. IL-10 mediated autoregulation plays a key role in controlling expansion of self-reactive B-1 cells.

Where are B-1 cells located?

Mouse B-1 cells are predominantly located in the peritoneal cavity, but are also found in the pleural cavity, the spleen, and the bone marrow, with little representation in lymph nodes or blood (23, 24).

How many B cell types are there?

There are four main types of B cells – transitional, naive, plasma, and memory – that all have their own purpose in the maturation process.

What’s the difference between B and T cells?

B cells produce and secrete antibodies, activating the immune system to destroy the pathogens. The main difference between T cells and B cells is that T cells can only recognize viral antigens outside the infected cells whereas B cells can recognize the surface antigens of bacteria and viruses.

How is humoral immunity activated?

The humoral immune response is mediated by antibody molecules that are secreted by plasma cells. To enter cells, viruses and intracellular bacteria bind to specific molecules on the target cell surface. Antibodies that bind to the pathogen can prevent this and are said to neutralize the pathogen.

How are B cells stimulated with CpG alone?

Little is known about the response of B cells stimulated with CpG alone, without additional cytokines. In this study, we show for the first time the phenotypic modification, changes in gene expression, and functional events downstream to TLR9 stimulation in human B cell subsets.

What kind of cells are responsive to CpG ODN?

In mice but not in humans, cells of the myeloid lineage, such as monocytes and myeloid dendritic cells, directly respond to CpG ODN, 14-17 leading to differences in the target cells activated and the cytokines induced by CpG ODN and limiting the extrapolation of results from mice to primates and humans.

How are CpG and CpG-B oligonucleotides differ in their effects?

The presence of PDCs in PBMCs was required for this CpG ODN-mediated effect. The expanded cells were cytotoxic and produced IFN-γ on peptide restimulation. Soluble factors induced by CpG-A but not CpG-B increased the granzyme-B content and cytotoxicity of established CD8 + T-cell clones, each of which was IFN-α/-β dependent.

What happens to IgM memory after CpG stimulation?

In addition, we demonstrate that upon CpG stimulation, IgM memory B cells differentiate into plasma cells producing IgM Abs directed against the capsular polysaccharides of Streptococcus pneumoniae. This novel finding proves that IgM memory is the B cell compartment responsible for the defense against encapsulated bacteria.