From The Desk Of Dr. Peter Ahlering: Validity Of NK Cell Testing

Due to recent information and review of many records in my office at MCRM Fertility, I have seen a variety of patients that have undergone unfortunate additional testing. I find it appropriate for me to initiate a blog to discuss reproductive immunology. Through my long history studying reproductive immunology, it is indeed just that “long”, I do have lots of interesting information and evidence to help people hopefully make sense of this significant controversy. The history of reproductive immunology and its applications to clinical management of patients with recurrent pregnancy loss, recurrent implantation failure, recurrent biochemical pregnancy losses, etc. is long and complex. This very problem creates a significant discussion out there about whether these treatments are at all efficacious for managing patients. The consensus in the reproductive medical world is that the foundation of reproductive immunology, as it applies to patient care, is flawed. It is not to say, at all, that the science and influence of immunology on reproduction is inaccurate or an unworthy endeavor. The science is incredibly robust and fascinating and has led to many insights into how implantation works. It is an ongoing science that is incredibly complex and is intimately tied to genetics, as well, these are the two most complex issues (immunology and genetics) in the realm of human medicine.

That said, the actual application of this knowledge to treating patients beneficially is very controversial and again the bulk of information simply says that treatments such as the usage of Intralipid, steroid therapy and antithrombotic medication (heparin, Lovenox and aspirin, etc.) simply do not have a positive effect on pregnancy outcome. These medicines certainly don’t have any significant evidence that indicate they are helpful for IVF failure, implantation failure, recurrent pregnancy loss, etc.

In addition, the real issue largely lies in the fact that we cannot test accurately to determine with any predictive capability whether a patient is going to fail in a future pregnancy based upon current blood work. In essence, the test that we use to try and predict a future outcome are fraught with problems and inaccuracies. The natural killer (NK cells) assay, APA testing and certainly (the worst offender) is the DQ and HLA testing. The natural killer cell assay, as evidenced by many papers and articles written over the years, is simply flawed in its particular capability. There are many issues behind this series of flaws, but that said it was never actually developed to be used for such purposes. It was in 1995, when there was some suggestion that it had some predictive capability for recurrent pregnancy loss patients, that it was adopted by some as a useful tool.

Again, that said, the NK assay is simply an inadequate and flawed test. Thus, the treatments that follow, the actions that one takes as determined by the results of this flawed test, are themselves going to be fraught with problems and issues on determining whether they actually work. So, consigning a patient to take Intralipid, Lovenox shots, aspirin and steroids based upon the results of an NK assay (which is indeed as said a flawed test) seems itself to be flawed treatments that are going to be very difficult to show that there is any actual benefit. Unfortunately, too many patients continue to be led down the path of having these tests completed and the resulting treatments, too. The end result for the patients is delayed time in more useful diagnostic review and treatment of their fertility condition and the unnecessary spending of several hundreds to thousands of dollars.

So, these issues that I have been looking at and have known for a long time have prompted me to initiate this conversation. I invite you to share your thoughts and questions regarding this topic. You may email me at or I welcome you to a consultation to review your complete situation in detail.