B cells are lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response, which is governed by T cells). B cells are an essential component of the adaptive immune system. B cells, which are the precursors of plasma cells, are characterized by the presence of a B-cell receptor able to bind specifically an antigen. Their principal functions are to make antibodies against antigens, perform the role of antigen-presenting cells (APCs) and eventually develop into memory B cells after activation by antigen interaction. Recently, a new, suppressive function of B cells has been discovered.

The abbreviation "B", in B cell, comes from the bursa of Fabricius in birds, where they mature. In mammals, immature B cells are formed in the bone marrow, which is used as a backronym for the cells' name.

Immature B cells are produced in the bone marrow of most mammals. Rabbits are an exception; their B cells develop in the appendix-sacculus rotundus. After reaching the IgM+ immature stage in the bone marrow, these immature B cells migrate to secondary lymphoid tissues (such as the spleen, lymph nodes, Peyer's patches, etc.) where they are called transitional B cells, and some of these cells differentiate into mature B lymphocytes.

Hong 10 (Real name: Kim Hong-Yeol, Hangul: 김홍열, born on 27 December 1984 in South Korea) is a male South Korean B-boy (also known as Breakdancer). His accomplishments include both a Red Bull BC One individual title (2006) and a Battle of the Year crew title (2002). He also was a judge at the 2007 Battle of the Year world finals.

The name Hong 10 comes from using a Korean language homonym and an English language pun. The second syllable of his name, Yeol, has the same pronunciation as the Korean pronunciation for the number ten. Therefore, pronouncing the phrase "Hong 10" in Korean will be the same pronunciation as his real name, Hong-Yeol. However, this nickname is always pronounced in English, so he is referred to as hong-ten regardless of the language context - whether Korean or English or otherwise.

Hong 10 was in the crew Expression (with which he won the Battle of the Year title in 2002) and is currently in a crew called Drifterz and a project team named Project Soul while he also performs as a solo dancer. Recently he formed a crew called 7 Commandoz with the world renowned bboys Ronnie, Differ, Skim, Wing, Menno, and Dyzee. This crew is known for their special Futuristic style. Recently, he has represented Jinjo Crew with fellow 7 Commandoz members Skim and Wing such as in the UK B-boy Championships 2009, Battle of the Year 2010, and R-16 Korea 2011.