Category Archives: Molecular Biology Genetic Disorders and Immunology

Non-T non-B lymphocytes

Some lymphocytes do not have characteristics of T or B cells, and although only malce up a small proportion of cells, may play an important role in immunity. Natural killer (NK) cells The role of NK cells is to eliminate tumour and virusinfected cells. This process is not antigen-specific. Many of the cells appear as large granular lymphocytes with an indented nucleus. The granules, which contain acid hydrola


GENETICS OF ANTIBODY PRODUCTION Antibody production is unusual in the following ways: 1 The molecule is encoded within three separate chromosomes: (a) Chromosome 14 for heavy chain (b) Chromosome 2 for K light chain (c) Chromosome 22 for ,\ light chain 2 Rearrangement of the multiple elements of germline DNA leads to production of antibodies with many different antigen-binding sites (clonal diversity of Fab) 3 Su

The cells of the immune system

Circulating leucocytes can be subdivided into several groups characterized on morphology, cell surface markers and biological function. There are two families of molecular structures on the cell surface called clusters of differentiation  and adhesion molecules . The biological function of many of the CD molecules is now known and knowledge of their presence is very useful in identifying specific leucocyte s

Organization of the lymphoid system

The immune system comprises several masses of lymphoid tissue or organs located throughout the body as well as circulating leucocytes. The circulating cells originate from the bone marrow and are ‘programmed’ to carry out specific functions by certain lymphoid organs. The principal lymphoid organs are as follows. Bone marrow The bone marrow is the primary site of haematopoiesis in  ammals. All bl

Regulation of complement activation Complement activation does not occur in the fluid phase, but is localized on the surface of the organism, cell or immune complex that triggered the reaction. This is essential, as many of the by-products of complement activation are potent mediators of inflammation, and would cause extensive tissue damage if not controlled. In addition to the activation sequences described,

The normal immune response-the immune system in health

The system is usefully divided into the innate and specific responses, although there is considerable interaction between these components. INNATE IMMUNITY This comprises the elements of the immune system that can mount a non-specific, ‘immediate’ response. These are directly activated by infectious agents, inflammation or tumours. The innate response has the advantage of speed, but lacks specific


Introduction Clinical immunology involves the investigation, diagnosis and management of diseases associated with abnormalities in the immune system. The most common problems are overactivity of the immune response leading to allergic and autoimmune disease, or underactivity resulting in immunodeficiency. Host defence mechanisms The immune system is made up of a complex network of cells, humoral factors and s

Human leucocyte antigens (HLA)

The HLA system consists of a series of closely linked genetic loci situated in the major histocompatibility complex (MHC) on the short arm of chromosome 6. shows the classification of these antigens. All loci are highly polymorphic, i.e. a large number of different alleles occur; more than 20 HLA-A, 50 HLA-B, 10 HLA-C, 15 HLA-DR, 3 HLA-DQ and 6 HLA-DP antigens have been identified so far. The class III senes

Applications of molecular genetics

The use of molecular biological techniques in genetics is having a massive impact on the investigation, diagnosis, treatment and control of genetic disorders. The avoidance and control of genetic disease Some genetic disorders, for example phenylketonuria or haernophilia, can be managed by diet or replacement therapy, but most have no effective treatment. By understanding what causes genetic damage potential m

Clinical genetics and genetic counselling

Genetic disorders pose considerable health and economic problems because often there is no effective therapy. In any pregnancy the risk of a serious developmental abnormality is approximately 1 in 30 pregnancies; approximately 15% of paediatric inpatients have a multifactorial disorder with a predominantly genetic element. People with a history of a congenital abnormality in a member of their family often see