Role of C3a and C4a Complement Proteins in Chronic Lyme Disease
August 12, 2014 in Science/Research by Ginger Savely, DNP
Readers of this publication are well aware of the controversies surrounding the diagnosis and treatment of Lyme disease. When the disease is missed in its early, easier-to-treat stage, it goes on to become a complex, multi-system disease that eludes diagnosis, mimics many other diseases, and requires aggressive, long-term treatment. Because the testing methods for Lyme and other tick-borne diseases are insensitive, many true cases of infection go undetected. Even when the diseases are detected, the unreliability of the testing makes it difficult to track treatment progress and test for cure.
Work by Drs Stricker and Winger identified CD57 positive natural killer cells as immune markers that tend to be low in chronic Lyme patients and increase with clinical improvement. An earlier article that I wrote for this publication explained how the measurement of CD57+NK cells in the blood has helped Lyme-literate health care providers in making the diagnosis of Lyme disease when tests are inconclusive. It has also provided a convenient marker to assist in following treatment progress and determining treatment end.
Although the CD57 marker has been a helpful tool, it has not been without its problems. We don't yet understand what confounding variables can skew the results. Some very sick patients start out with normal or above-normal CD57 levels. Other patients' levels stay low and never increase with treatment, despite the fact that they are symptom-free and otherwise seem completely cured. There may be large day to day variation in the CD57 level as I observed in a study looking at twice daily blood draws over 3 days for both Lyme patients and well patients. The level can increase or decrease as much as 50% within the same day. So the CD57 level can be a useful marker for some patients but it is not always reliable and consistent.
Enter C3a and C4a, the new kids on the block in the world of Lyme diagnosis and treatment. The "C" in C3a and C4a stands for complement. Complement proteins work with antibodies to destroy pathogens. They activate immunity through control of inflammation, phagocytosis (ingestion of pathogens by white blood cells) and cell death by lysis (breaking of the cell membrane). There are about 30 of these complement proteins that circulate in the bloodstream making up complement "cascades", so called because activation of one protein initiates activation of the next, etc.
Dr. Ritchie Shoemaker and his colleagues published a study in 2008 reporting elevated C3a and C4a levels in acute Lyme disease. Many patients who contract Lyme disease do not develop the diagnostic "bull's eye rash", and Lyme tests are frequently negative shortly following a tick bite when prompt diagnosis is crucial for effective treatment. Shoemaker et al. suggested that elevated C3a and C4a levels can serve as early markers in the diagnosis of acute Lyme disease.
Because CD57+ NK cell levels are not always reliable markers for chronic Lyme, there is an ongoing search for new biomarkers to aid in the diagnosis of chronic, disseminated Lyme disease and to follow treatment progress. Dr. Stricker and I recently published a study in the Scandinavian Journal of Immunology comparing C3a and C4a levels of chronic Lyme patients to those of healthy controls, AIDS patients and patients with systemic lupus. The C3a complement protein level was normal in the AIDS patients, the healthy patients and the chronic Lyme patients. So, although C3a was shown to be elevated in a cohort of early, acute Lyme disease patients, it appears to be normal in chronic Lyme patients.
In our study, only the systemic lupus patients had elevated levels of C3a. Other published studies have associated elevated C3a with autoimmunity as well. Therefore, the C3a may prove to be a useful marker in differentiating ongoing symptoms due to an autoimmune process versus an ongoing infectious process.
For purposes of our C3a/C4a study, Dr. Stricker divided the chronic Lyme patients into two groups: 1) those with primarily musculoskeletal symptoms (MSK) and 2) those with neurological symptoms severe enough to warrant treatment with intravenous antibiotics. Interestingly, C4a levels were significantly elevated in the MSK group, but only slightly (and not statistically significantly) elevated in the neurologic group. C4a levels were also elevated in the AIDS and systemic lupus groups, but not in the healthy controls. In Lyme patients with elevated C4a, the levels decreased in those who responded well to antibiotic treatment. Those patients who did not improve on antibiotics (more often than not, the severe neurological group) had no statistically significant reduction in their C4a levels.
Keep in mind that almost all chronic Lyme patients have some degree of neurological involvement. The neurological Lyme patients in the study who did not have elevated levels of C4a were those with severe cognitive dysfunction as evidenced by abnormal blood flow to areas of the brain noted on their SPECT brain scans. Examples of these patients are those who presented with symptoms mimicking Alzheimer's disease, multiple sclerosis, Parkinson's disease, or Autism Spectrum Disorder. Amyotrophic lateral sclerosis (ALS) patients do not have cognitive deficits and, in fact, Lyme patients with this type of severe neurological presentation did have elevated C4a levels.
The normal range for the C4a is zero to 2830. In my chronically ill Lyme patients I have seen C4a levels as high as about 26,000. However, most of my patients start with a pre-treatment level between 6000 and 12,000. In the two years that I have been using the C4a test to track treatment progress, reduction in C4a levels has consistently correlated with clinical improvement.
Patients often ask if there are other medical conditions that may lower or raise the C3a and/or C4a. Both of these complement products may be increased in normal pregnancy and in certain types of vasculitis (an inflammatory condition that destroys blood vessels). C4a levels are elevated in adult insulin dependent diabetes. Those who suspect that chronic fatigue syndrome (CFS) may actually be misdiagnosed Lyme disease may not be surprised to hear that C4a is also elevated in CFS patients. In fact the C4a is probably elevated in all sorts of infections, and therefore is not specific to Lyme.
If you would like your health care provider to order your C3a and C4a levels, it is extremely important that the tests be performed only at the National Jewish Medical and Research Center Laboratory in Denver. LabCorp has a contract with National Jewish and therefore your health care provider can order LabCorp tests # 840702 (C3a) and # 857334 (C4a). LabCorp uses two different send-out labs for the test and it is important to indicate that samples should be routed to National Jewish for most accurate results. Ask your health care provider to write on the requisition slip in large letters: "ACCESSIONING: C3a & C4a MUST BE ROUTED TO NATIONAL JEWISH". To find the LabCorp drawing station nearest you, go to www.labcorp.com and enter your city or zip code in the space provided in the lower left of the home page.
If your health care provider writes the ICD-9 (diagnostic) code of 279.3 (Immune dysregulation) on your LabCorp requisition slip, insurance will more than likely cover the C3a and C4a tests. However, if your insurance does not cover the tests, the prices are not prohibitive. Each of the tests cost $ 75.60 (valid as of 3-25-09).
Because most lab technicians are unfamiliar with the C3a and C4a tests, it is in your best interest to go to the LabCorp drawing station knowing exactly how your blood should be handled. This way you will be assured that your sample will arrive at the lab satisfactory for testing. The blood needs to be drawn into an EDTA tube ("lavender top") and immediately spun and separated. The plasma should be frozen right away and sent frozen to National Jewish.
The C4a is not as specific to chronic Lyme as the CD57+ level because it may be elevated in many types of infection, including other tick-borne diseases. However, in patients with known tick-borne infections, the C4a complement protein test can provide a useful way to determine initial degree of infection, to follow treatment progress and to aid in deciding upon treatment end. For more information about the C3a and C4a, please see the suggested readings below: