Lymphocyte Responses In Vitro


Lymphocytes can be stimulated in vitro to undergo many of the responses associated with antigen stimulation in vivo. The development of in vitro activation protocols has led to the identification of important cellular communication pathways and to a molecular description of lymphocyte function.

Keywords: lymphocyte activation; T cell; B cell; antibody production; cytokines

Figure 1.

Contrasting conventional T‐cell activation with polyclonal in vitro methods. In response to peptides presented with major histocompatibility complex (MHC) on the surface of an antigen‐presenting cell (APC), a small number of T cells will engage the T‐cell receptor (TCR) and transduce a signal that acts in concert with signals from other (cos) to induce (IL‐2) receptor expression, and IL‐2 to be secreted. A similar sequence of events can be induced without the unique, limiting participation of a peptide. Superantigens bridge the peptide vacant MHC of an APC to the TCR. Allo‐MHC presents a sufficient range of novel MHC–peptide combinations that a high frequency of T cells can be stimulated. Plant lectins bind and crosslink glycoproteins on the T‐cell surface involved in activation. Oxidation leads to the permanent chemical crosslinking of cell surface glycoproteins and subsequent uncontrolled receptor triggering. Antibodies directed against the TCR, CD3 or costimulatory receptors can crosslink the target molecule and induce activating signals. In the membrane bypass protocol pharmaceutical agents cross the membrane and activate intracellular signalling cascades directly. Irrespective of the method used, all procedures result in IL‐2‐driven T‐cell proliferation.

Figure 2.

Three modes of B‐cell activation in vitro. (1) When activated conventionally by the (TI‐1) stimulus lipopolysaccharide (LPS), (BCRs) help to focus the mitogen to the cell surface and thereby trigger additional activating receptors. Antigen receptor stimulation, however, will inhibit immunoglobulin secretion. High LPS concentrations in vitro bypass the need for any involvement of surface immunoglobulin and induce rapid proliferation and cytokine‐independent immunoglobulin secretion. (2) TI‐2 antigens form crosslinking lattices with the antigen receptor of specific B cells. The signals generated synergize with cytokines to induce proliferation and immunoglobulin secretion. These physiological signals are commonly reproduced in vitro using anti‐immunoglobulin antibodies. (3) The conventional pathway of T‐dependent (TD) activation involves a sequential dialogue between T and B cells. The B cell first captures antigen, internalizes it and traffics degraded peptides to the surface in association with the MHC class II. (2) Specific T cells are activated and, in response to the stimulus, express cell surface molecules, including the ligand for CD40, de novo. In addition, the T cell secretes cytokines (3). In response to both CD40 engagement and signalling from cytokine receptors, the B cell proliferates and secretes immunoglobulin (4). These processes can be shortcircuited by engaging CD40 directly with CD40 ligand or anti‐CD40 antibodies and adding cytokines to culture exogenously.



Gett AV and Hodgkin PD (1998) Cell division regulates the T cell cytokine repertoire, revealing a mechanism underlying immune class regulation. Proceedings of the National Academy of Sciences of the USA 95: 9488–9493.

Herman A, Kappler JW, Marrack P and Pullen AM (1991) Superantigens: mechanisms of T cell stimulation and role in immune responses. Annual Review of Immunology 9: 745–772.

Knight SC, Iqball S, Roberts MS, Macatonia S and Bedford PA (1998) Transfer of antigen between dendritic cells in the stimulation of primary T cell proliferation. European Journal of Immunology 28: 1636–1644.

Lenschow DJ, Walunas TL and Bluestone JA (1996) CD28/B7 system of T cell costimulation. Annual Review of Immunology 14: 233–258.

Mosmann TR and Coffman RL (1989) Heterogeneity of cytokine secretion patterns and functions of helper T cells. Advances in Immunology 46: 221–261.

Parker DC (1993) T cell‐dependent B cell activation. Annual Review of Immunology 12: 331–360.

Seder RA and Paul WE (1994) Acquisition of lymphokine‐producing phenotype by CD4+ T cells. Annual Review of Immunology 12: 635–673.

Smith KA (1990) The interleukin 2 receptor. Annual Review of Cell Biology 5: 397–425.

Snapper CM and Mond JJ (1993) Toward a comprehensive view of immunoglobulin class switching. Immunology Today 14: 15–17.

Trapani JA (1998) Dual mechanisms of apoptosis induction by cytotoxic lymphocytes. International Review of Cytology 182: 111–192.

Uemetsu Y, Ryser S, Borgulya P, Krimpenfort P, Berns A, von Boehmer H and Steinmetz M (1988) In transgenic mice the functional T cell receptor beta gene prevents expression of endogenous beta genes. Cell 52: 831–841.

Weiss A, Imboden J, Shoback D and Stobo J (1984) Role of T3 surface molecules in human T‐cell activation: T3‐dependent activation results in an increase in cytoplasmic free calcium. Proceedings of the National Academy of Sciences of the USA 81: 4169–4173.

Further Reading

Janeway CA and Travers P (eds) (1996) Immunobiology – The Immune System in Health and Disease, 3rd edn. Oxford: Blackwell Science.

Paul WE (ed.) (1993) Fundamental Immunology, 3rd edn. New York: Raven.

Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite close
Hodgkin, Philip Desmond(Apr 2001) Lymphocyte Responses In Vitro. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0001187]