Differentiation in the direction of the B-cell starts with the pre-B-cell in the bone marrow. On the next stage of maturation, the cell is called mature B-cell. The mature B-cell circulates around the organism and enters peripheral lymphoid organs (lymph nodes, spleen).
B-lymphocytes make only 10%-20% of the lymphocytes in the circulation. They are carriers of humoral immunity and are directly responsible for producing antibodies.
The cells in the circulation have immunoglobulins and complement receptors on their surface. Owing to antigenic stimulation, activation, proliferation and transformation occur in the germinative center. During transformation, surface immunoglobulin, cytoplasmatic immunoglobulins, and complement receptors can easily be detected. Transformed B-lymphocyte leaves the germinative center as a large immunoblast. Surface immunoglobulins and complement receptors disappear, and intracytoplasmic immunoglobulins appear.
The immunoblast continues the division, migrates towards medullary cords and transform themselves into plasmocytoid lymphocytes, plasma-cells, and small “memory” B-lymphocytes that, after the repeated antigenic stimulation, are subjected again to activation and transformation in the germinative center. Plasma-cells produce large quantities of immunoglobulins, and release them in the bloodstream indirectly via the lymph.