Serological Techniques Study Notes

Definition: Serological techniques involve using the serum or the fluid portion of a person's blood.
Objective: The main focus in serological testing is the detection of antibodies.

Procedure Manual:
- Each medical laboratory procedure is documented in a procedure manual.
- This document outlines current techniques and approved policies, and it must comply with CLSI format, an agency overseeing medical laboratory science.
- The manual is always available at the laboratory bench for reference.
Blood Specimen Preparation:
- Blood or specimen preparations involve dealing with serum, which is obtained from blood.
- Anticoagulated evacuated tubes (red top or gold top) are used.
  - Serum is allowed to clot at room temperature, removing clotting factors (like fibrinogen).
  - After clotting, the tube is spun down to separate the serum from red blood cells.
- Transfer the serum portion to a new, properly labeled tube:
  - Label contents should include:
    - Type of specimen (serum)
    - Patient details (name, date of birth, testing required)
    - Draw date and time,
    - Initials of the person who transferred the serum.
Storage of Serum Samples:
- Serum samples can be refrigerated for testing within 72 hours.
- Alternatively, serum can be frozen for long-term storage.

Lipemia:
- Presence of excess lipids results in a milky serum appearance, potentially interfering with test results.
Hemolysis:
- Occurs when red blood cells are broken down, exposing their contents (interferes with tests).
Bacterial Contamination:
- Presence of bacteria makes the specimen unacceptable for testing.
Icteric Serum Samples:
- Indicates excess bilirubin in the specimen, giving it an orange color.
Complement Activity:
- Complement proteins help eliminate microorganisms, but may interfere with certain tests and need to be inactivated when necessary.

Types of Pipettes Used in the Lab:
- Manual Pipettes (with twist or bulb mechanism)
  - Important to draw samples to the meniscus (the lowest point of the sample's curve).
  - Method involves:
    - Inserting the pipette tip below the waterline.
    - Wiping the tip with gauze after withdrawal.
    - Adjusting the pipette to the meniscus level.
    - Excess sample should be drained into the receiving vessel.
- Automatic Pipettes (Micropipettors):
  - More commonly used in medical laboratory science.
  - Operation involves two plunges:
    - The first plunge fills the pipette.
    - The second plunge empties the pipette completely.
    - Important to reach the second stop when emptying.

Single Dilution:
- Defined process where a portion (1 mL) of a sample is added to a diluent (9 mL of saline).
- Resulting ratio is referred to as a 1 to 9 ratio, making a total volume of 10 mL.
- The dilution factor is the denominator, which in this case equals 10.
Serial Dilution:
- Involves taking a diluted sample and further diluting it step by step while maintaining a consistent ratio.
- Example process:
  - Add 1 mL of sample into 1 mL of diluent for a first dilution of 1 to 2.
  - Then take 1 mL from the first tube and add it to another 1 mL of diluent for a second dilution of 1 to 4.
  - Continuing this process generates further dilutions (1 to 8, 1 to 16, etc.).
  - Recognized as a twofold serial dilution (multiplier of two).
  - If multiplier were four, it would be termed a fourfold serial dilution.

Antibodies and Antigens:
- Focus of serological techniques primarily revolves around antibodies present in the serum.
- Acute phase: When a patient is currently sick.
- Convalescent phase: When a patient has recovered.
- Further information on antibodies and antigens will be provided later.

Understanding of these serological techniques, specimen handling, pipetting, and dilution methods is crucial as this content will be elaborated on in subsequent classes, aiding in the comprehensive knowledge of medical laboratory science.