In an article published in PLOS ONE, Professor Jean-Paul Viard, MD, from the Assistance Publique–Hôpitaux de Paris, and colleagues, explore a potential link between higher basal vitamin D levels in HIV-positive patients and a stronger immune response to hepatitis B and Streptococcus pneumoniae vaccination.
Vitamin D has previously been shown to be involved in regulating the body’s immune response. According to the authors of the study, immune cells present in the innate, as well as adaptive immune response, have been shown to possess receptors for vitamin D, suggesting the involvement of vitamin D in modulating immune responses. According to Professor Viard and colleagues, earlier work has suggested that deficiency in vitamin D leads to higher vulnerability to infections, such as tuberculosis, and that taking vitamin D supplements could help patients overcome respiratory tract infections. In addition, previous work has implicated vitamin D deficiencies in HIV-infected individuals with unfavorable disease progression.
According to the authors, earlier studies conducted in mice demonstrated that administering vitamin D as a supplement during vaccination increases the efficacy of the immune response. As a consequence, Professor Viard and his colleagues sought to discern the relationship between levels of vitamin D and the immune response in immunocompromised patients, specifically in those infected with HIV. The researchers reasoned that if a positive correlation were to be found, supplementing vaccines with vitamin D would be a simple and innocuous way to boost a patient’s immune response to vaccines.
The researchers obtained data from two vaccine-related clinical trials conducted in HIV-infected patients. One trial involved a recombinant HBV vaccine and included 339 patients. The other trial administered a vaccine targeting Streptococcus pneumoniae and included 25 patients. In patients that qualified for the study, the authors analyzed levels of 25-hydroxyvitamin D (25OHD), the chief form of vitamin D in circulation, in blood plasma utilizing a radioimmunoassay method.
Blood plasma levels were quantified as being sufficient, insufficient, and deficient. To determine the immune response to the vaccinations, the anti-hepatitis B antibody response was measured for the patients who received the hepatitis B vaccine and anti-pneumococcal antibody for those who received the anti-pneumococcal vaccine. For the hepatitis vaccine, the immune responses were quantified and patients were labeled as non-responders, low responders, and high responders. A high responder is someone whose immune response to the vaccine bestows the patient with long-term immunity. On the other hand, someone who is a low responder has a sufficient enough anti-hepatitis titer level to be protected against infection but not on a long-term basis.
In order to determine the relationship between the two variables, the authors utilized a logistical modeling tool and adjusted for additional variables like age, gender, and smoking status.
The results indicated that no significant correlation existed between the level of 25OHD in blood plasma and a patient’s immune response to the vaccines. In other words, higher base levels of vitamin D were not associated with a stronger immune response in HIV-infected patients.
The authors conceded that these results may not be applicable to the general population since the study only included HIV-positive patients. However, they pointed to a previous study which examined vitamin D levels and antibody response to influenza and found no positive correlation as well. In addition, Professor Viard and his colleagues are wary to recommend vitamin D supplements to boost immune responses since vitamin D has also been shown to have anti-inflammatory properties which may hinder the body’s immune response to vaccination.