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Haematology summray 9


Chapter 9 in Haematology (White cells: lymphocytes) summary

-Lymophcytes are immunologically comptent white cells that are involved in antibody production  (B cells) and with the body's defence against viral infection or other foreign invasion (T cells).

-They arise from haemopoietic stem cells in the marrow, T cells being subseqently processed in the thymus.

-B cells secrete gammaglobulin antibodies specific for individual antigens.T lymphocytes are further subdivided into helper (CD4+) and cytotoxic (CD8+)cells .They recognise peptides on HLA atigens.Natural killer cells are cytoxic CD8+ cells that kill target cells with low expression of HLA molecules.

-The immune response occurs in the germinal centre of lymph nodes and involves B-cell and T-cell proliferation, somatic mutation, selection od cells by recognition of antigen on antigen-presenting cells and formation of plasma cells (which secrete immunoglobulin)or memory B cells.

-Immunoglobulins includes five subcalsses or isotypes, igG,igA,igM,igD, all madeup of two heavy chains and two light chains .

-Complement is a cascade of plasma proteins that can either lyse cells or coat (opsonise)them so they are phagocytosed.

-Lymphcytosis is usually caused by acute or chronic infection or by lymphoid leukaemias or lymphomas.

-Lymphadenopathy may be localizaed (bacause of local infection or malignancy) or generalized becaused of infection, non-infectious inflammatory diseases, malignancy or drugs.

 

 

From book: Essentail Haematology A.V.HOFFBRAND,P.A.H.MOSS.6EDITION
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