All naive b cells are different only one out of this

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All naive B-cells are different only one out of this bunch that will bind to a particular foreign antigen. When an antigen first appears only a few B-cells can bind; if they bind it creates a signal transduction reaction which leads to this cell being induced to divide into a whole population of cells called clonal specificity . They only recognize that particular antigen now and out of the whole population there are two types: plasma B-cell and memory B-cells which stay in circulation for a long time. It takes about ten days to two weeks to get to this population. Antibodies are tetramers with a short chain called the light chain and a long chain called the heavy chain . There is a variable region that changes in different antibodies and a constant unchanging region. FC region = fragment crystallisable region. o Antibodies: are immunoglobulin NOT globin protein families which are composed of four polypeptides with two long heavy chains and two short light chains. Two ‘arms’ can bind two antigens and if you bind two you can get a complex put together and antigens can clump together which is known as agglutination NOT coagulation. After agglutination: After agglutination phagocytes (macrophages which means big eaters or dendritic cells [discovered at McGill]) can easily engulf the clump. Natural killer cells (NK lymphocytes) destroy the cells marked with antibodies which recognized the FC side so it knows that it has been marked by an antibody which means it is invaded. o It makes a protein caused perforin (looks like tin can) and puts a hole in the cell killing it where calcium is involved. BIOLOGY 103 February 3 rd , 2017 LECTURE #12 Cat Stevens “The First Cut is the Deepest” There is an activation of complement which is a cascade reaction. The binding leads to activation of complement proteins which assemble to form a ‘LEGO donut’ to puncture the pathogen o The humoral response works after detection the foreign antigen by antigens provided by a B-cell, but they do not actually kill the pathogen. o The binding leads to activation of complement and subunits assemble into a donut to make a pore in the membrane of the invading cell and it will die. o Phagocytosis is where a macrophage engulfs after agglutination response.
Ops onization makes the antigens more ‘tasty’ for the macrophages. i-Clicker Question: We may need to recognize maybe up to a million “foreign” antigens in our life time. How is this accomplished? o We have hundreds of thousands of genes encoding hundreds of thousands of different antibodies. o We don’t have enough genes to code for all of these antigens and that is why we die from many diseases. o There must be some kind of interesting story during B lymphocyte development that explains this mystery.

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