Immune status is a set of laboratory indicators that characterize the quantitative and functional activity of the cellular and humoral arms of the immune system. Assessment of immune status is carried out with the help of laboratory examination - immunogram. Blood immunogram does not selectively reflect the state of a pathologically altered organ or system, but allows you to assess the immune system as a whole (the cumulative effect of changes in the activity of the immune system in response to foreign antigens). 

Determination of the cellular composition (immunophenotyping) of blood lymphocytes is the main component in the assessment of immune status, which is performed by flow cytofluorimetry. Immunophenotyping of leukocytes consists in the detection of differentiation markers, or CD-antigens, on their surface. Leukocytes express a number of surface and cytoplasmic antigens unique to their subpopulation and stage of development. CD-antigens (cluster of differentiation antigens) are antigens on the surface of cells, markers that distinguish certain cell types from others. The differentiation of these antigens has been studied and sta ndardized, and they have been assigned specific numbers. CDs can be recognized using appropriate monoclonal antibodies.

• B-lymphocytes (CD19+CD3-) abs. and rel.
  
• True natural killer cells (NK cells) (CD3-CD56+) abs. and rel.
  
• T-lymphocytes (CD3+CD19-) abs. and rel.
  
• T-helper/inductors (CD3+CD4+) abs. and rel. 
  
• T-cytotoxic lymphocytes (T-CTL) (CD3+CD8+) abs. and rel.
  
• T-lymphocytes expressing NK-cell markers (T-NK cells) (CD3+CD56+) abs. and rel.
  
• Activated T-lymphocytes (CD3+HLA-DR+) abs. and rel.
  
• Activated T-lymphocytes (CD3+CD25+) abs. and rel.