The Immune system is a series of complex procedures which has evolved to protect the organic structure from onslaught by foreign pathogens. These pathogens are able to come in our organic structure through the tegument or liner of the internal variety meats. The immune system is able to protect us from intracellular and extracellular beings every bit good as from ourselves, halting malignances and autoimmune diseases from distributing in our organic structures ( Bastian, 1993 ) . There are two lines of defense mechanism, the adaptive ( specific ) and unconditioned ( non-specific unsusceptibility ) , though both are united in their end to destruct pathogens they have different ways to undertake this. Innate unsusceptibility is the first line of defense mechanism while adaptative unsusceptibility is the 2nds line and therefore takes longer to move ( Clancy, 1998 ) . The complement system is portion of the immune system and can be bought into action by the adaptative system if required. Complement is a group of proteins working together within the immune system ; one time stimulated by one of many triggers, peptidases begin to split protein in the system, conveying a cascade of enzyme reactions in order to contend off foreign pathogens and activate the inflammatory response. Within the complement cascade there are many proteins that play a function but C3 is a protein critical to the effecter maps of the system ( Abbas, 1994 ) .

There are many waies for immune mediated lysis and the 1 we will be looking at is intravascular haemolyse and occurs when the complement has been triggered through the classical tract. When the antibody binds to the antigen on the surface of the red blood cell, a complement constituent triggers the membrane onslaught composite to organize pores in the cell membrane ensuing in cell lysis ( Chapel, 1990 ) . The strength and velocity at which cells lyse is dependent upon the rate at which the complement cascades to enable complete cell lysis.

Experiments like these are able to supply us with an apprehension of how the complement immune system maps. It can besides increase our apprehension of autoimmunity and possibly take to ways in which the effects of unsusceptibility can be prolonged or inhibited harmonizing to the disease. Systemic Lupus Erythematosus ( SLE ) is an autoimmune disease, in which complement is analysed, as acquiring SLE is dependent upon the cistron which is responsible for bring forthing MHC, a constituent used in hemolysis ( American, 1993 ) , patients with other immunological upsets can necessitate their complement activity to be monitored and therefore this check would be able to demo how expeditiously the complement constituent of the immune system is working to support their organic structures.


To find complement serum activity by lysing sheep red blood cells

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To find the volume of complement required for 50 % lysis.


20 Cuvettes 1.0ml

20 trial tubing plastic disposable

Automatic pipette 200-1000 Aµl & A ; 6 tips

Automatic pipette 0-200 Aµl & A ; 6 tips

Water bath at 37oC


Test tubing rack


Ice pail & A ; Ice


Wash 4ml of red blood cell suspension three times with barbital saline solution.

Fix a 6 % stock solution of red blood cells

In one trial tubing mix

3.0ml of sheep anti-erythrocyte antiserum, diluted 1/50

3.0ml of the 6 % SRBC

Mix and gently by cresting and inverting several times

Incubate at 37oC for 15min in the H2O bath, mix every 5min.

Set up the trial tubing on ice in extras and label

Add the reagents in order as shown in table 1 below

Incubate the tubing for 60 proceedingss at 37oC blending gently every 15minutes

Topographic point the tubings on ice and so centrifugate at 200g for 10 proceedingss at 4oC

Remove the samples and set into cuvettes and read the optical density at 541nm, with ammonia solution as space record the consequences in a tabular array.

Table: Tubes for Assay

VOLUME OF REAGENT ( milliliter )








( Blank )

Buffer ( milliliter )







Guinea-pig Serum ( milliliter )

Initial dil. 1:30

( look into this has been diluted already! ! )







Sensitised red blood cells ( milliliter ‘ ) suspension

( as prepared in portion II above ; NOTE this will be given you )









When transporting out the experiment natural information was recorded, and presented in table 1. However the consequences obtained during the practical were non used as the red blood cells lysed before complement was added and hence complement activity could non be observed as adding complement to lysed cells is non able to bring forth consequences, therefore the ideal informations provided was used and analysed.

From table 1 it is clear that optical density degrees increased as serum volume increased, this is due to the fact that as volumes of complement addition more ruddy blood cells are lysed which in bend allows haemoglobin to be let out, this is of a dark coloring material and as more cells are lyses the darker the ensuing sample will be, and so the optical density as read the spectrophotometer will increase. After the guinea hog serum has been mixed with the allergic red blood cells, it produces anti-body coated cells with complement attaching to the antibody, and triping this attracts the MAC molecules to take action and lyse the cell ( Kuby, 1994 ) . Following the form seen in table one tabular array 3 shows a progressive % lysis of cells as the volume of serum is increased, nevertheless for the 100 % lysis an ammonium hydroxide buffer was used to guarantee that all cells are lysed during the experiment.

Further to this graph 1 produced a sigmoid curve, from which it was possible to gauge CH50. However ciphering the 50 % lysis from this graph is non really accurate. Thus a log graph 2 was constructed, with the usage of new wave Krogh equation to find the existent value of 50 % lysis. The equation was provided by the lector.

Van Krogh equation:

x= K [ y ] 1/n



x= sum of complement ( milliliter of undiluted serum )

y= proportion of cells lysed

k=50 % unit of compliment

n=inclination of graph ( ideally 0.2 )

This resulted in table 4 giving a volume of 133.5 CH50/ml. However when ciphering CH50 the ten values were all in the negative. Furthermore, it was non possible to compare informations sets obtained against ideal informations as the experiment did non give consequences due to lysis of red blood cells before complement was added. This could hold occurred due to improper pipetting, managing or transporting of the cells as agitating them excessively much could hold lysed them due to floor, as the cells were sensitized and therefore prone to quick lysis. Further to this it was reported by Inglis, et Al, 2007, that the usage of red blood cells from different sheep can give inaccurate consequences and therefore bring forth different CH50. Although there are many inaccuracies present within the experiment, it besides gives range to further better the method every bit good as explore other country of the topic at manus such as factors which affect the public presentation of complement like temperature or PH. This check is a good manner to mensurate the activity of the immune system within patients, such as patients with LSE as mentioned earlier, other patients with low unsusceptibility can besides be tested to see how the complement system is or is n’t helping their recovery, therefore stairss can be taken by medical professionals to either encouragement or supervise the advancement of the patients unsusceptibility as basically the immune system is required to work at its optimum to maintain worlds and animate beings from deceasing of disease ( Inglis, et Al, 2007 ) .


Overall this experiment has shown how complement is of import in helping white blood cells to lyse foreign organic structures. Though in the experiment carried out the blood cells lysed before complement was added the method was presented and the ideal set of informations, showed what consequences should hold been obtained. Besides the hypothesis that as the complement concentration additions so will the optical density proved positive.


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