The two major types of lymphocytes are B cells and T cells. B lymphocytes are responsible for humoral immunity and are precursors to plasma cells. T lymphocytes are responsible for cell mediated immunity. T lymphocytes have various types of regulatory functions. Without special immunohistochemical stains, it is impossible to distinguish lymphocyte types morphologically.
Plasma cells are responsible for production of immunoglobulins.
The primary role of lymphocytes is in immune functions. Immunoglobulin is an important opsonin. Lymphokines are soluble products of lymphocytes which mediate a variety of processes. Major lymphokines involved in inflammation include chemotactic substances and cell growth and proliferation factors. Inflammatory and immune processes occur concurrently and are highly interdependent.