A summary of the development, diversity and functionality of B cells

Satisfactory Essays
The immune system is a complex collection of cells fundamental to the survival of an organism via protection against pathogens such as viruses, bacteria and parasites [1]. It does this while also recognising “self from non-self” as not being able to make this distinction can lead to serious problems known as autoimmune diseases where the immune system attacks itself. There are two major forms of immunity, the innate and the adaptive immune systems. The innate system is an ancient form of immunity that recognises pathogens through highly conserved features known as pathogen-associated-molecular-patterns (PAMPs). It’s considered the first line of defence and found in even the most primitive of animals [2]. Innate immunity is comprised of various different cells such as neutrophils, monocytes, macrophages and the compliment system [2]. The second type is known as the adaptive immune system and is considered the hallmark of immunity in higher animals [2]. It differs from innate immunity primarily in its specificity but also in its use of immune cells, activation and effectiveness. Whilst innate immunity relies on common patterns in its targets such as bacterial cell wall components for recognition, adaptive immunity relies on specific interactions with structures called antigens and two primary adaptive cell types, B and T cells. This review will focus on B cells, the antibody producing cells of adaptive immunity. B cells primarily work as producers of antibodies, molecules that target foreign pathogens in a specific manner through a cell surface structure known as an antigen. Antibodies begin life as low-affinity molecules and through various recombination and mutation processes they develop into functionally diverse m...

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...ey have yet to encounter their specific antigens. These naïve mature cells also express IgD due to its mRNA chain being transcribed from the same transcription unit as IgM. IgD is lost upon antigen activation [20]. The function of IgD is elusive but it is generally believed to be a key modulator of the humoral immune response [22]. All maturation before this point is termed antigen-independent maturation due to the lack of antigen interaction. Naturally the following section deals with the antigen dependent portion of B cell development. Another important feature of these naïve B cells is the presence of IgM antibodies, the first antibody to be produced and also the least diverse. These antibodies provide an early response to antigens through low binding affinity and can later undergo class switch recombination to one of the more diverse antibody subtypes available.