What is the Difference Between Serum Protein Electrophoresis and Immunofixation

The main difference between serum protein electrophoresis and immunofixation is that serum protein electrophoresis can determine the quantity of monoclonal protein, whereas immunofixation cannot determine the quantity of monoclonal protein. 

Serum protein electrophoresis and immunofixation are two techniques for separating and detecting monoclonal proteins in the serum. 

Key Areas Covered

1. What is Serum Protein Electrophoresis
– Definition, Technique, Importance
2. What is Immunofixation
– Definition, Technique, Importance
3. Similarities Between Serum Protein Electrophoresis and Immunofixation
– Outline of Common Features
4. Difference Between Serum Protein Electrophoresis and Immunofixation
– Comparison of Key Differences

Key Terms 

Immunofixation, Serum Protein Electrophoresis

What is Serum Protein Electrophoresis

Serum protein electrophoresis is a technique that detects the presence and quantity of albumins and globulins in the serum. It is important to detect multiple myeloma. There are two major proteins present in the serum. They are albumin and globulin. Albumin is the major protein component of the serum and gives a high peak in serum protein electrophoresis. Also, globulins occur in smaller fractions in the serum. Five globulin categories occur in the serum. They are alpha-1, alpha-2, beta-1, beta-2, and gamma globulin. Here, the albumin peak lies close to the positive electrode, while the peak of the gamma globulin lies close to the negative electrode.

Figure 1: Normal Serum Protein Electrophoresis

Furthermore, in serum protein electrophoresis, blood is collected, and the separated serum of the blood is electrophoresed. Electric current separates the serum protein components.  

What is Immunofixation

Immunofixation is the technique that allows the detection of monoclonal antibodies or immunoglobulins in the serum or urine. It is also important for the detection of myeloma. Importantly, when soluble antigens are mixed with the corresponding antibody, they precipitate, and the precipitation is visible under the naked eye or the microscope. Therefore, immunofixation detects the presence of immunoglobulin isotopes in the serum and urine. First, immunoglobulins in the sample are fractionated according to the electrophoretic mobility. For the precipitation, specific antisera are used for the target antibodies.

Figure 2: Immunofixation

Moreover, the sample deposits on a gel in the first step. The application of the electric current separates the sample according to the charge and size.   

Similarities Between Serum Protein Electrophoresis and Immunofixation

• Serum protein electrophoresis and immunofixation are two techniques for separating proteins in the serum.
• They detect the presence of specific proteins in the serum and urine.
• They are important in detecting myeloma. 

Difference Between Serum Protein Electrophoresis and Immunofixation

Definition

Serum protein electrophoresis refers to an easy, inexpensive method of separating proteins based on their net charge, size, and shape. In contrast, immunofixation refers to detecting and typing monoclonal antibodies or immunoglobulins in serum or urine.

Significance

Serum protein electrophoresis can detect the presence and the quantity of proteins in the serum, while immunofixation can detect only the presence of proteins in serum and urine. 

Importance 

Serum protein electrophoresis detects serum proteins, including globulin and albumin, while immunofixation detects immunoglobulins in the serum and urine. 

Sensitivity

Serum protein electrophoresis is less sensitive, while immunofixation is more sensitive.

Myeloma

11% of the myeloma patients have normal serum protein electrophoresis, while immunofixation is done when the clinical suspicion of myeloma is high.  

Conclusion

In brief, serum protein electrophoresis and immunofixation are two techniques to detect monoclonal proteins in the serum and urine. Serum protein electrophoresis is a technique to separate proteins according to the net charge, size, and shape. Also, it detects the presence and quantity of proteins in the serum. Additionally, it detects the serum proteins such as albumin and globulin. However, it is less sensitive in detecting proteins, and 11% of myeloma patients have normal serum protein electrophoresis. In comparison, immunofixation is the detection of immunoglobulins in the serum and urine. But it can only detect the presence of monoclonal proteins. Importantly, immunofixation is a more sensitive method of detecting proteins. It is done in high clinical suspicion of myeloma. Therefore, the main difference between serum protein electrophoresis and immunofixation is the ability to quantify proteins. 

References:

1. Sherilyn Alvaran Tuazon, M. (2023, May 24). Serum protein electrophoresis. Reference Range, Interpretation, Collection and Panels.
2. Immunofixation. Immunofixation – an overview | ScienceDirect Topics. (n.d.). 

Image Courtesy:

1. “Serum protein electrophoresis normal” By Steven Fruitsmaak – Own work (CC-BY SA 3.0) via Commons Wikimedia
2. “Immunfixation schematisch” By EssEmLink – Own Work (CC-BY SA 4.0) via Commons Wikimedia