Agglutionation of Red Blood Cells by Natural Antibodies in Blood Plasma of Different Animal Species

What was the aim of this experiment?

To test agglutination of RRBC in different animal species and the role of IgM versus IgG.

What are natural antibodies?

Antibodies present in the bloodstream without prior exposure to specific antigens.

What is agglutionation?

The clumping of antigenic particles (e.g., RRBC) by antibodies.

What is alpha-gal

A sugar antigen found on many animal and bacterial cells but absent in humans and chickens.

Why do humans and chickens have high anti=alpha-gal antibodies

They lack the gene to produce alpha-gal, so they recognize it as foreign.

What is the function of 2-mercaptoethanol in the experiment?

It degrades IgM while leaving IgG intact, allowing the role of IgM in agglutination to be assessed.

What was observed after treating plasma with 2-mercaptoethanol

Agglutination titers decreased by at least three steps, confirming IgM’s primary role in agglutination.

Which species had the highest agglutionation titers?

Humans (8) and chickens (7).

What is the significance of anti-alpha-gal antibodies in immune defense?

They help recognize bacterial cells containing alpha-gal, contributing to the first line of defense.

What were the conclusion of the experiment

Both hypotheses were confirmed: IgM is the dominant agglutinating antibody, and humans and chickens have the strongest response due to their immune recognition of alpha-gal.

Rabbit red blood cells (RRBC)

Contain many different antigenic determinants (epitopes)

RRBC has alpha-gal epitope

Most mammals have alpha-gal as antigen on cells

Human and chicken do not have alpha-gal epitopes

In human 1% of all antibodies binds alpha-gal

Natural antibodies

Present in blood without intentional immunisation

Natural antibodies binding RRBC

Natural anitbodies binding alpha-gal

• first line of defence against parasites

• Rejection of pig heart

  • red meat hypersensitivity

Ttiter

A measure of how much a sample can be dilutred before antibodies can no longer be detected