Immunology Flashcards
Explain coombs test.
The Coombs’ test is used to detect antibodies that act against the surface of your red blood cells. The presence of these antibodies indicates a condition known as hemolytic anemia, in which your blood does not contain enough red blood cells because they are destroyed prematurely.
There is a direct and indirect coombs test
Explain direct coombs test.
AIM– to detect the antibodies bound to the RBC membrane
(to search AB on RBC cell
RBC having Antibody attatched to the antigen= We give Coombs reagent
(which have the AB against the immunoglobin(human antibody IgG, IgM or the complement protiens)
agglutination occus with the human immunoglobins attached to the antigen on the rbc membrane.
If the hemolysis is occurring rapidly n the body then coombs test could come out negative.
(10% of people with warm autoimmune hemolytic anaemia will have a negative coombs test)
explain indirect coombs test
AIM - To search AB in the plasma
Take patients plasma in test tube )it contains unknown AB that we need to find out)
we will then put RBC (know antigen as we know what we are looking for)
after putting RBC there can be two scenarios- either the AB in plasma will attach to RBC anigen or not
we will then but Ab against immunoglobins and if the form agglutination the test is positive and vice versa
What is the main diff between Direct and indirect coombs test?
Direct-
detect AB and complemets ON surface of RBC
uses- Autoimmune hemolysis
drug induced hemolysis
alloimmune (hemolyic disease of the newborn)
Indirect-detect ONLY antibodies in the serum (cannot detect compliments as they are only active when bind to RBC)
uses-
pre transfusion testing (blood types, cross matching)
pre natal antivody screening
Explain Cold agglutination disease.
Type of autimmune hemolytic anaemia
cold antibody IgM
Intravascular hemolysis is seen
RBC,s will aglittinate in the vessels of the extremeties causing Acrocyanosis (blue fingers)
causes can be G6PD
