3.2.1 Earlier antigen-independent phase

The first phase of B-cell differentiation and maturation would be antigenindependent. It takes place in the bone marrow and results in the generation of immature B-cells expressing pair L chains with μ chains to form cell surface monomeric IgM in association with transmembrane Igα and Igβ invariant chains, forming the BCR complex, which is able to recognize and capture antigens.
