Which best describes the stage of development of the B cell

Which best describes the stage of development of the B cell above the question mark? VI.C VI O Stem Cell O Pro-B Cell Pre-B Cell Immature B Cell Mature B Cell

Solution

Answers: -

1.option \"b\"-Pro-B cell.

Explanation: -

**Lymphoid progenitor cells receive signals from bone marrow stromal cells to begin B cell development.

**Cytokines induce TdT and recombinase (RAG-1 and RAG-2) synthesis in CD34⁺ lymphoid progenitors.

**The cells undergo D-J joining on the H chain chromosome to become early pro-B cells and also begin expressing CD45 (B220) and Class II MHC.

**Joining of a V segment to the D-J_H completes the late pro-B cell stage.

**Pro-B cells become pre-B cells when they express membrane m chains with surrogate light chains in the pre-B receptor.

2.option \"b\"-B 7 molecules.

Explanation: -

**Immature dendritic cells may also phagocytose small quantities of membrane from live own cells, in a process called nibbling.

**Once they have come into contact with a presentable antigen, they become activated into mature dendritic cells and begin to migrate to the lymph node.

**Immature dendritic cells phagocytose pathogens and degrade their proteins into small pieces and upon maturation present those fragments at their cell surface using MHC molecules.

**Simultaneously, they upregulate cell-surface receptors that act as co-receptors in T-cell activation such as CD80(B7.1), CD86 (B7.2), and CD40 greatly enhancing their ability to activate T-cells.