Lymphocytes

B cells

These guys bind to antigens on invading cells, and then transform into lots of plasma cells, making antibodies. Sometimes they need a T Helper cell to provide some proteins to help them finish the transformation.

B Memory Cells

Some cells, instead of becoming plasma cells, become memory cells, which 'remember' specific antigens, meaning that the immune response can be faster the next time.

T Cells

These float about the body until an antigen presenting cell attracts teir attention. On seeing a foreign antigen, the T cell divides and proliferates, forming 3 types of T cell, shown below:

T Helper Cell (CD4)

These cells have two functions:

• To help B cells produce antibodies
• To help T-Cytotoxic cells come to antigens - by releasing cytokines like interleukins.

These cells respond to MHC - 2 (major histocompatality complex). They are well known for reducing in number in AIDS.

T Cytoxic Cell (CD8)

Also known as T Killer Cells, these cells secrete perforin and granzymes to apoptose cells. They respond to the cytokines released by Helper cells, and to antigens with the MHC - 1 marker.

T Memory Cells

Become memory cells, which 'remember' specific antigens, meaning that the immune response can be faster the next time. Very long lived