Hormones Improve Immune Response to HBV Vaccination in Aged Animals.(Brief Article)

2001 MAY 16 - (NewsRx.com & NewsRx.net) --

Preclinical results with a Hollis-Eden Pharmaceuticals, Inc. (HEPH) investigational drug candidate, HE2200, an immune-regulating hormone, demonstrated that HE2200 and other immune-regulating hormones given to aged mice concurrently with a hepatitis B vaccine significantly improved immune responses to the vaccine, as measured by the amount of vaccine-specific antibody.

Response to hepatitis B vaccine in aged animals is being used as a model system for analyzing the ability of immune-regulating hormones to correct immune dysregulation in the elderly.

In addition to enhanced antibody responses, the drug candidates demonstrated a correction from the depressed cell-mediated immunity (Th2 bias) of aged mice to the balanced Th1/Th2 response seen in young animals. The results of the study were presented in an abstract and poster session at the 4th Annual Conference on Vaccine Research held April 23-25, 2001, in Arlington, Virginia.

Results from the experiment demonstrated that administration of hepatitis B vaccine to young animals resulted in vaccine-specific antibody titers that were approximately five-fold higher (2500 ng/ml on day 21) compared to untreated aged animals (approximately 500 ng/ml on day 21). Aged animals given HE2200 in conjunction with the hepatitis B vaccine produced vaccine-specific antibody titers that were more than four-fold higher (approximately 2200 ng/ml on day 21) than those seen in untreated, aged mice and approached the levels achieved in young mice. In addition, administration of HE2200 to aged mice showed a correction of the Th2-bias seen in untreated aged mice (immunoglobulin G1 (IgG1) to IgG2a ratio of 28 to 1), to the more balanced Th1/Th2 ratio seen in young animals (IgG1 to IgG2a of 8 to 1).

In healthy young adults, there are two types of adaptive immunity that exist in balance: Th1, or cell-mediated immunity, and Th2, or humoral immunity. The Th1 branch of the immune system is responsible for controlling intracellular invaders such as viruses and certain parasites, while Th2 immunity includes the humoral response necessary for controlling extracellular pathogens such as certain bacteria. Both types of immunity are critical to a well functioning immune system; however, the ability to mount a strong cell-mediated response is frequently lost in the elderly and in patients suffering from chronic infectious diseases such as HIV. Immune-regulating hormones have been shown to be part of the body's natural regulatory mechanism for the cytokines and dendritic cells that drive Th1/Th2 balance. These same immune-regulating hormones have also been shown to be depleted in the elderly and in a variety of other conditions of immune dysregulation, suggesting that a ...