Task

Blood Typing Virtual Lab

Scenario

A break-in and burglary occurred at a jewelry store. The investigators noted several glass displays were smashed and glass was scattered throughout the store. Small pieces of blood-stained clothing were left behind. These were collected and sent to the lab for analysis.

The Evidence

Three suspects have been apprehended and blood samples have been collection from each.

After confirming that the samples are indeed stained with blood, your job at the laboratory is to analyze the samples collected from the scene to determine the blood type on the evidence as well as the blood type of the three suspects.

Let's go down to the lab to walk through the procedure.

The Lab

In your lab, you have a blood sample and three reagents.

  • a serum with synthetic antibody-A
  • a serum with synthetic antibody-B
  • a serum with synthetic antibody-Rh
A small red bottle labeled blood, a blue bottle labeled antibody-A serum, a yellow bottle labeled antibody-B serum, and a clear bottle labeled antibody-Rh serum,

When the antibody serums are added to a blood sample with the given antigen, they agglutinate, or clump. We can use that knowledge to determine a blood type.

Three wells. In all, there is a light pink liquid with either large irregular or small uniform circular dark red clumps.

See the visible darker red spots and clear areas in the samples above? That's agglutination.

Start the Test

Start by adding the blood sample to each of the three marked wells in the sample tray.

Open Add Patient Blood Sample in a new tab

Now, take the antibody-A serum and add it to the blood sample in the wells.

Open Add Antibody-A Serum in a new tab

Blood well showing blood in A well with light areas and longer dark clots

Do you see agglutination? Yes or No?

Answer: Yes. Do you see the clumps? That's agglutination. Since you see agglutination, you know that A antigens are present.

Possible Blood Types

You know that A antigens are present. So, what blood types (A+, A−, B+, B−, AB+, AB−, O+, and/or O−) could be on this evidence?

Answer: Based on the presence of A antigens, the blood could be A+, A−, AB+, or AB−.

Antibody B Test

We can narrow the blood type down farther by testing for the B antigen. Add the antibody-B serum to the blood sample.

Open Add Antibody-B Serum in a new tab

Blood well showing blood in B well with consistent smooth red color

Do you see agglutination?

Answer: No. Do you see any clumps? Since you do not see any clumps (hence, no agglutination), you know that B antigens are not present.

Possible Blood Types

You know that A antigens are present and B antigens are not present. With this new information, what blood types (A+, A−, B+, B−, AB+, AB−, O+, and/or O−) could this be?

Answer: Based on the presence of A antigens and absence of B antigens, we have narrowed the blood types to A+ or A−.

Antibody Rh Test

We make our final determination of blood type by testing for the Rh antigen. Add the antibody-Rh serum to the blood sample.

Open Add Antibody-Rh Serum in a new tab

Blood well showing blood in Rh well with clear areas and large patchy clots

Do you see agglutination?

Answer: Yes. Since you see clumps and, therefore, see agglutination, you know that Rh antigens are present.

Possible Blood Types

You know that A and Rh antigens are present and B antigens are not present. With this new information, what blood type (A+, A−, B+, B−, AB+, AB−, O+, or O−) is present?

Answer: Since the evidence contains A and Rh antigens, it is A+ blood. Remember this when examining the suspects.

The Suspects

Investigators have identified three potential suspects. Knowing the blood type will allow investigators to narrow down these potential suspects further.

Suspect 1 - Testing

Start by adding the blood sample to each of the three marked wells in the sample tray.

empty blood well with blood samples and serums behind it.

Add all three antibody serums to the tray. Look at the sample.

Blood sample with blood in antibody-A well smooth and uniformly red, in antibody-B blood is pinkish with small circular red clumps, and in antibody-Rh blood has thick red flakes with small clear patches.

Which antibodies show agglutination?

Answer: The antibody-B and antibody-Rh serum caused agglutination.

Suspect 1 - Blood Type

You know that B and Rh antigens are present. So, what blood type (A+, A−, B+, B−, AB+, AB−, O+, or O−) is our suspect?

Answer: Since Suspect 1 has B and Rh antibodies, his blood is B+.

Suspect 2 - Testing

Start by adding the blood sample to each of the three marked wells in the sample tray.

empty blood well with blood samples and serums behind it.

Add all three antibody serums to the tray. Look at the sample.

Blood well showing blood in Rh well with clear areas and large patchy clots

Which antibodies show agglutination?

Answer: The antibody-A and antibody-Rh serum caused agglutination.

Suspect 2 - Blood Type

You know that A and Rh antigens are present. So, what blood type (A+, A−, B+, B−, AB+, AB−, O+, or O−) is our suspect?

Answer: Since Suspect 2 has A and Rh antibodies, his blood is A+.

Suspect 3 - Testing

Start by adding the blood sample to each of the three marked wells in the sample tray.

empty blood well with blood samples and serums behind it.

Add all three antibody serums to the tray. Look at the sample.

Blood sample with blood in antibody-A well that is smooth and uniformly red, in antibody-B blood is smooth and uniformly red, and in antibody-Rh blood has think red flakes with small clear patches.

Which antibodies show agglutination?

Answer: Only the antibody-Rh serum caused agglutination.

Suspect 3 - Blood Type

You know that Rh antigens are present. So, what blood type is our suspect?

Answer: Since Suspect 3 has Rh antibodies only, his blood is O+.

Choose a Suspect

Now, we have the blood type from the evidence (A+) and our three potential suspects.

  • Suspect 1: B+
  • Suspect 2: A+
  • Suspect 3: O+

Based on this information, which suspects can be eliminated?

Answer: Suspects 1 and 3 can be eliminated as their blood type does not match that found at the scene.

You have successfully identified the blood types of the suspect and released two innocent suspects.