Oops, you're using an old version of your browser so some of the features on this page may not be displaying properly.

MINIMAL Requirements: Google Chrome 24+Mozilla Firefox 20+Internet Explorer 11Opera 15–18Apple Safari 7SeaMonkey 2.15-2.23

Immunoglobulins and B-Cell Development

Chapter 1: The Immune System

Immunoglobulins and B-cell Development Figure 1

Source: Fix D., Professor at Southern Illinois University

The lymphocytes developed in the BM (B-cells) have as their final task the production of Ag-specific immunoglobulins (Ig), which function as antibodies (Ab).

Ig are proteins secreted by or present on the surface of B-cells, assembled from identical couples of heavy (H) and light (L) chains.

The highly variable N terminal regions are the Ag-binding portion (Fab fragment). The constant domains interact with the Fc receptors on the effector cells.


There are 5 classes of Ig: M, G, A, E, and D, distinguished by different heavy chains. B-cells can change the class of Ig produced: class switch.

Before being capable of producing Ag-specific Ig, B-cells must undergo a number of transformations, first in the BM and subsequently in the LNs.

In the rest of the cells in the body (not B-cells), the genes encoding for the H and L chains of the Ig are distributed in many segments so that they cannot be expressed.


These gene segments must be rearranged within the chromosome in the B-cells so the final gene structure allows the expression of a functional protein.

The first stages of B-cell development occur in the BM, where pro-B-cells first rearrange the Ig H chain gene to become a pre-B-cell.

Pre-B-cells continue this somatic recombination process by rearranging the L chain to become an immature B-cell, expressing IgM on their surface.

Revision Questions

  1. What are the Fab and the Fc portions of an immunoglobulin?
  2. What distinguishes a pre-B from a pro-B from an immature B-cell?
  3. What is meant with the term “somatic recombination”?
Chapter 1 - The Immune System B-Cell Diversity

This site uses cookies. Some of these cookies are essential, while others help us improve your experience by providing insights into how the site is being used.

For more detailed information on the cookies we use, please check our Privacy Policy.

Customise settings