Vitamin D Binding Protein (VDBP), also known as Gc protein, is a multifunctional protein whose main role is to carry vitamin D and its metabolites, but it also acts as an actin scavenger1 and is the precursor of the macrophage activating factor molecule (GcMAF), which has reported highly promising results against cancer, HIV, and neurological disorders including autism, Alzheimer's disease, Chronic Fatigue Syndrome (CFS), among others. Nagalase has been published as a biomarker associated with various types of cancer 2,3,4,5,6 systemic lupus erythematosus7, influenza8, and human immunodeficiency virus infection (HIV)9. It is enzymatically distinct from hepatic galactosaminidase and appears to be far more biologically active.
Nagalase is a component of viral hemagglutinin and is released by the action of trypsin on hemagglutinin.10 Hemagglutinin is a common glycan-binding lectin of many viruses (including influenza, paramyxoviruses and polyomaviruses), several viruses may individually or jointly contribute to hemagglutinin-derived Nagalase activity in the blood.11 In the absence of recent viral infection or malignancies, elevated nagalase activity likely represents a marker of viral production of hemagglutinin protein being acted upon by inflammatory cell mediated trypsin activity; as such, it may represent viral persistence, active transcription, and inflammation.11
According to RED Laboratories in Belguim, nagalase (α-N-acetylgalactosaminidase) is an enzyme that deglycosylates the Gc protein or vitamin D binding protein. The Gc protein is thereby rendered incapable of conversion into active GcMAF. As a result, the regulation of macrophage activation is prevented. The nagalase reaction with Gc Protein results in a deglycosylated Gc protein product that prevents the formation of GcMAF and consequent activation of macrophages. Nagalase is produced by many cancer cells and some bacterial and viral pathogens and is a mechanism whereby cancer cells and other pathogens attempt to avoid the host's immune system. Nagalase measurements in blood are used as a diagnostic tool, such as, for example, to monitor tumor burden during cancer diagnosis and therapy as well as in autism therapy.12
Activity of nagalase in serum or plasma is determined through a proprietary method consisting of a two-step immunocapture assay. Nagalase is known to inactivate GcMAF and its natural precursor Gc-globulin. It is proposed that patients could be treated with substitution therapy with GcMAF and nagalase has been projected as marker (indicator) of effectiveness for the GcMAF therapy.
Apparent nagalase activity in serum or plasma is measured kinetically at RED Laboratories through conversion of a fluorogenic substrate in function of time. The test is standardized against a large serum pool of carefully selected healthy persons (normal WBC count, no inflammation, CRP <1mg/L, no clinical history of immune disease or diabetes); the apparent nagalase activity measurement allows one to establish a normal range of substrate conversion between 0,5 and 0,95 nMol/ml/min for adults.
RED Laboratories' extensive research in this field, however, revealed that the measurement of the apparent nagalase activity only reflects the nagalase activity as potential inactivating enzyme activity in serum/plasma for GC-MAF, but it does not reflect the total nagalase activity in serum, because with the measurement through fluorogenic substrate conversion one should take into account the amount of natural substrates present in the serum/plasma which compete for the substrate conversion in RED Laboratories' assay. The known natural substrates for nagalase are
GcMAF (at very low concentration ng/ml);
Gc-globulin (at high concentration on average 620 mg/L in serum); and
Blood group A substance (in extremely high concentrations in total blood due to the amount of RBC, but only in low concentrations in serum or plasma).
The amount of natural substrate for nagalase present in tissues is not currently known. This situation leads to the conclusion that the apparent nagalase activity is not a good biomarker to measure the breakdown of GcMAF in the blood of patients and we should consider the presence of natural competitors of nagalase in order to establish the total nagalase content in serum/plasma. The main natural competitor we can measure in blood is the Gc-globulin concentration, which may vary between 150 and 1500 mg/L. The Gc-globulin concentration may affect the GcMAF concentration in two ways: first as being the precursor to GcMaF affecting the buildup of GcMaF through the activating enzyme cooperation on B and T lymphocytes and secondly as a major competitor for nagalase preventing the breakdown of GcMAF.
In short, many diseases are associated with increased levels of nagalase, which deglycosylates VDBP so that it cannot convert to Gc-MAF, thus leading to immunosuppression.
RED Laboratories in Belgium is one of the few laboratories offering nagalase testing. The results for nagalase testing done at RED Laboratories are reported as a group containing the values for
apparent nagalase activity;
corrected nagalase activity (i.e. effective nagalase activity) in function of the major natural substrate competitor Gc-globulin and
an alternative immunomodulation enzyme for which RED Laboratories has chosen Dipeptidyl-peptidase or CD26 present on T and B lymphocytes and macrophages as well as in numerous other cell populations in the body. The normal range values have been established for children, adolescents and adults.