Immunochemistry

Marvel of serum protein analysis

ImmunochemistryImmunochemistry is dedicated to analysing proteins in biofluids using a variety of techniques (electrophoresis, immunofixation,  viscosity, turbidimetry and/or RID).

Monoclonal Gammopathy

Plasma cells syntheses and assembles immunoglobulin from two heavy and two light chains thus producing 5 types (IgG, IgA, IgM, IgD and IgE) and this can be further types as being kappa or lambda based on the light chain.

Monoclonal gammopathies: A disease state associated with a single plasma cell producing elevated levels of an immunoglobulin of a single class and type, known as monoclonal proteins, M-proteins or paraproteins. These can be of a benign nature or of uncertain significance and in some cases, indicate a malignancy, such as multiple myeloma or Waldenström’s macroglobulinaemia. These must be differentiated from polyclonal gammopathies seen as secondary due to clinical disorders such as chronic liver disease, collagen disorders, rheumatoid arthritis and chronic infection. These abnormal plasma proteins are filtered by kidney and appear in the urine thus providing valuable insight not only into the type of protein but also the renal function.

These can be easily seen as abnormal electrophoretic pattern. A suggested work-up for full characterisation includes measuerement of IgG, IgA, IgM, IgD; B2M; albumin, total protein, densitometry (paraprotein quantitation), cryoglobulin; viscosity; immunofixation; Kappa and Lambda light chains and Creatinine.


Initially B-cell abnormalities can be visualised by electrophoresis, this will show elevated levels of protein with different mobilities. In this example, the immunoglobulin abnormalitites is seen as a band in the far left-hand side track (for comparison see the track on the near-left which is normal (included for reference purposes)). The abnormal band will require further investigation to determine the type of immunoglobulin present.

Further investigation of serum abormalities, seen during intital electrophoresis, can reveal various combination of paraprotein which are examplified below.

Kappa paraproteinaemia

IgG (Kappa)

Patient: 84 years old male

Diagnosis/History: 

  • Aortic valve replacement
  • Bladder carcinoma insitu
  • Hypothyroidism following excision of thyroid adenocarcinoma
  • Lower back and hip pain following recent fall rehabilitation centre
  • Acute coronary syndrome

Laboratory data:

All immunology parameters were within the normal range except for:

  • CRP was elevated (11.9 mg/l)
  • Normal immunoglobulin
  • Serum Fix revealed IgG Kappa paraprotein

The serum abnormaility seen above during electrophoresis is resolved by immunofixation and it is clear that this serum has IgG Kappa paraproteinanaemia. 

IgA (Kappa)

Patient: 73 years old male

History: Myeloma presentation for clinical trial

Laboratory data:

All immunology parameters were within the normal range. The following were abnormal:

  • Beta-2-Microglobulin (5.6mg/L)

  • IgA (36.7 g/L - raised)
  • IgM (0.27g/L - decreased)
  • Serum creatinine (106 umol/L)

Immunofixation demonstrates IgA Kappa paraproteinaemia in patients serum coinciding with B region.

IgM (Kappa)

Patient: 62 years old female

History/Diagnosis: IgM MGUS

Laboratory data: 

All immunology parameters were within the normal range. The following were elevated:

  • IgM (15.25g/L)
  • Serum viscosity (1.76 mPAS)
  • Immunofixation of serum demonstrated IgM Kappa paraprotein

Patient was diagnosed as having MGUS

Lambda paraproteinaemia

IgG (Lambda)

Patient: 53 years old male

History/Diagnosis: IgG Lambda paraprotein

Laboratory data: 

The following were parameters were outside the range:

 

  • IgG (16.58 g/L - borderline elevated)
  • IgA (0.29g/L, decreased)
  • IgM (0.3 g/L, decreased)
  • Serum creatinine (116 umol/L, borderline elevated)

Immunofixation of serum shows IgG Lambda paraprotein

IgA (Lambda)

Patient: 73 years old female

History/Diagnosis: IgA Lambda paraprotein

Laboratory data: 

All parameters were normal except for:

 

  • IgA (4.36g/L, elevated)
  • Immunofixation of serum demonstrated IgA Lambda paraprotein

IgM (Lambda)

Patient: 64 years old male

History/Diagnosis: IgM Lambda paraprotein

Laboratory data: 

All parameters were normal except for:

  • IgM (3.58g/L, elevated)
  • Immunofixation of serum demonstrated IgM Lambda paraprotein

IgD and IgE are less common paraproteins and usually a fix which detects Kappa or a Lambda that does not correspond to IgG, IgA or IgM suggests further investigation into the possibility of the presence of IgD or IgE. These can be missed due to antigen excess and may require several dilutions of serum.

 This is an example of the fix that needs further investigation and below are examples of IgD and IgE paraproteins detected using this approach.

IgD (Kappa)

Patient: 53 years old male

History/Diagnosis: IgD Kappa paraprotein

Laboratory data: 

The following were parameters were outside the range:

  • IgD (5.9 g/L - elevated)
  • IgA (0.44g/L, decreased)
  • IgM (0.12 g/L, decreased)
  • CRP (17.7mg/L elevated)

IgE (Lambda)

Patient: 59 years old male

History/Diagnosis: IgE Kappa paraprotein

Laboratory data: 

The following were parameters were outside the range:

  • IgE (989,000 KU/L - elevated)
  • IgG (2.95g/L, decreased)
  • IgA (0.12g/L, decreased)
  • IgM (0.09 g/L, decreased)
  • Beta-2-Microglobulin (7.6mg/L, elevated)
 

MGUS (monoclonal gammopathy of unknown significance)

MGUS is a non-cancerous (benign) condition which resembles multiple myeloma and similar diseases without any symptoms or problems. No treatment is indicated but regular moniotring is recommended as only a small number of people may go on to develop more serisous problems.

Patient: 78 years old female

History/Diagnosis: Meyloma presentation

Laboratory data: 

All the parameters were normal and within the range except for:-

 

Minimal IgM Lambda paraprotein was detected in the serum using electrophoresis.