Antisera: –

As it is known that A group contained in its serum component which react with B antibody while the B group contained in its serum component that react with A antigen.

This serum component is known as antisera.

A —— Anti B —–B group

B ——Anti A ——A group

These sera are available in market.

The antisera made from the human serum is called polyclonal antisera.

Now a days due to HIV disease scientist has discovered the synthetic sera which is known as monoclonal antisera.

In forensic the analysis of blood grouping from the crime exhibits is very important. For the analysis of blood from cloth the small portion of the blood cutting must be taken. But to analyze blood grouping from soil or weapon the thread must be prepared from the exhibits.

Preparation of Thread: –

The clean cotton thread is put in normal saline (the concentration of normal saline is 85% sodium chloride).

The wet thread is rubbed on weapon gently or on the soil particle and dry in the oven at 70 degree Celsius for 1-2 hours.

The antigen will be fixed on the thread and it can be processed for grouping.

Find out species origin it is not essential to dry the thread.

Different Types of Method: –

A B O blood group from fresh blood

  1. Forward Method: –

Take a 3-cavity slide.

Put one drop of Anti A, Anti B, Anti H serum.

Add one drop of about 2 % cell suspension in each cavity and mix the contained thoroughly.

The clumping can be seen in the blood which it belongs to

A B O Blood group
Clump ——- ——- A
——- Clump ——- B
——- ——- Clump O

Due to it substance is a precursor to A B group substance sometimes clumping with its sera might see apart from A / B group but can say that the blood group is of A group only.

  1. Reverse Method: –

Let the whole blood clot remove the serum carefully.

Take a 2-cavity slide and mark A and B.

Add one drop of 2% cell of A and B cell.

Examine the contents for the presence of agglutination.

A B Antibody Blood group
+ ——- Anti B A
——- + Anti A B
+ + O
  1. Absorption Elution Method: –

In this technique the Ag Ab reaction.

Take place on thread in cool condition.

Antisera have 2 sites one will attached to Ag and other will remain open.

Antigen Antibody complex will form in cool condition.

The complex is eluted at 55 degree Celsius.

The open side of the antisera will react with known cells and that Ag Ab reaction see in the media.

There are 2 methods for absorption elution method.

  1. Test tube Method: –

Take 3 clean and dry test tubes and mark as A B O.

Cut the blood stain and put about 2 mm or 2.5 mm long thread in each test tubes.

Dip the fabric in Anti A serum Anti B serum and Anti H and keep at 4 degree Celsius.

Remove the Antiserum and give 3-4 washing with ice chilled normal saline.

After the last wash remove whole of normal saline and add one drop of fresh normal saline.

Plug the test tube with cotton swab and keep in water bath at 56-60 degree Celsius for 15-20 minutes.

Add 1 drop of 2-5% A B O indicator cell in the respective tubes and keep at 4 degree Celsius for half an hour. The result can be seen in stereomicroscope after centrifugation.

Result: –

Agglutination in A test tube ——— A blood group

Agglutination in B test tube ——— B blood group

Agglutination in O test tube ——— O blood group

Precaution: –

Washing should be done with ice chilled saline.

At the time of elution 1 drop of saline is required.

  1. Cellulose Acetate Method: –

Take a cellulose acetate sheet (minimum thickness 0.4 mm) and mark 3 areas and exhibit name.

Fix the thread on 3 area which are marked.

Put 1 drop of Anti A serum Anti B serum and Anti H serum respectively on fixed thread.

Place the sheet in moist chamber and allow it to absorb overnight at 4 degree Celsius in refrigerates.

Next day remove the excess antisera with chilled saline flow and keep to sheet in chilled saline for 1 hour.

Remove from the chilled saline and blot dry with blotting paper.

Put 1 drop of saline to each thread and keep sheet in moist chamber at 55 degree Celsius.

Add 1 drop of 6 % cell suspension of A B O to respectively on the fixed thread.

The result can be seen in stereomicroscope.