The diagram to the right depicts lymphocyte activation and interactions with antigen-presenting cells. The adaptive immune system involves:
Helper T cells (CD 4+): A subset of T lymphocytes that interact with HLA class II glycoproteins from APC cells. Upon proper binding, Helper T cells help to activate CD8+ T cells and CD19+ B lymphocytes.
Cytotoxic T cells (CD 8+): A subset of T lymphocytes that interact with HLA class I glycoproteins from nearly all nucleated cells and release granules to induce apoptosis of infected cells.
B lymphocytes (CD 19+): An APC that processes non-self antigens for CD4+ T helpers for activation and differentiation to produce antibodies against a specific pathogen.
Plasma cells (CD 27++): Activated/differentiated B cells that produce antibodies directed against a specific pathogen.
- The two pluses in CD 27++ indicate strong positivity or a high expression of the CD27 marker on plasma cells.
2. Häggström, Mikael. "Medical gallery of Mikael Häggström 2014 - Lymphocyte activation (more detailed)." WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.008. ISSN 2002-4436. 2014.
