Agglutination

•  In infectious mononucleosis, the patient exhibits-  Atypical lymphocytes in the circulating blood.

– Antibodies to the EB Virus.

– Increased heterophile antibody titre.

• The normal titre of agglutinins and hemolysins in human blood against sheep red blood cells does not exceed 1:8, but in infectious mononucleosis the titre may rise to 1:4096.
• This is referred to as positive Paul Bunnel test and is both characteristic and pathognomic of the disease.

The direct version of the Coombs test would be performed to determine if the infant has maternal IgG (anti-Rh) already bound to the erythrocytes in the  cord  Blood.  IgG  antibodies  are  relatively small. When they coat large particles or cells, such as  erythrocytes, they  do  not  readily agglutinate them. In the direct Coombs test, anti- immunoglobulin (antibody against the Fc region of human IgG) is directly added to the infant’s erythrocytes. The anti-immunoglobulin (also known as Coombs reagent) spans the distance between cells to form an agglutinating lattice that can be visualized in the test tube.

Agglutination

Latex agglutination

Agglutination

Ans. is ‘b’ i.e., Agglutination test

Ans. is ‘b’ i.e., Widal test

Heterophilic ag^glutination reaction

. Some organisms of different class or species share closely related antigens.

.  When serum containing agglutinin (antibody) of one organism gives agglutination reaction with antigen of other organism, it is called heterophilic agglutination test.

Examples are

.   Streptococcus M.G. agglutination test for primary atypical pneumonia.

.  Weil – Felix reaction for typhus fever

.  Paul Bunnell test fin- IMN.

Ans. is ‘c’ i.e., Slide flocculation

Ans. is ‘a’ i.e., Widal test

.                              Widal test is a tube agglutination test.

.                              Other three options are precipitation tests.

Ans. is ‘a’ i.e., Agglutination test

• Paul Bunnell test is tube agglutination test.

Ans. is ‘b’ i.e., Is a tube agglutination test 

Ans. A: It is less sensitive than precipitation reaction for detecting antibodies

The primary reaction is the binding of the Fab portion of antibody to antigenic determinants on the particulate antigen. The secondary reaction is the result of the cross-linking by multivalent antibodies, of the particles of multivalent antigen to form aggregates.

The foregoing two-component system can in certain instances be enhanced by the addition of a third component, complement (C’). This is exemplified by the reaction of immune hemolysis, in which the antibody “sensitizes” erythrocytes which are then lysed by complement.

The most obvious clinical application of agglutination is blood-typing; erythrocyte blood group surface antigens (e.g., the ABO blood group factors) react with antibody that is specific for these allo-antigens to produce agglutination. The cross- matching of blood depends upon this technique.

The surface antigens of bacteria also react with appropriate antibodies to produce agglutination. A patient’s serum can be tested for the presence of antibody to known antigens of certain bacteria (e.g., Salmonella typhi), giving diagnostically significant information.

Ans B is Donor serum tested against recipient packed cells

(Method shown: cross matching of blood groups) 

Cross-matching (or crossmatching) blood, in transfusion medicine, refers to the test that is performed prior to a blood transfusion in order to determine if the donor’s blood is compatible with theblood of an intended recipient