Cellular immune responses to Neisseria meningitidis in children

There is an urgent need for effective vaccines against serogroup B Neisseri a Meningitidis. Current experimental vaccines based on the outer membrane p roteins (OMPs) of this organism provide a measure of protection in older ch ildren but have been ineffective in infants. We postulated that the inabili ty of OMP vaccines to protect infants might be due to age-dependent defects in cellular immunity, We measured proliferation and in vitro production of gamma interferon (IFN-gamma), tumor necrosis factor alpha, and interleukin -10 (IL-10) in response to meningococcal antigens by peripheral blood monon uclear cells (PBMCs) from children convalescing from meningococcal disease and from controls. After meningococcal infection, the balance of cytokine p roduction by PBMCs from the youngest children was skewed towards a T(H)1 re sponse (low IL-10/ IFN-gamma ratio), while older children produced more T(H )2 cytokine (higher IL-10/IFN-gamma ratio). There was a trend to higher pro liferative responses by PBMCs from older children. These responses,were not influenced by the presence or subtype of class 1 (PorA) OMP or by the pres ence of class 2/3 (PorB) or class 4 OMP, Even young infants might be expect ed to develop adequate cellular immune responses to serogroup B N. meningit idis vaccines if a vaccine preparation can be formulated to mimic the immun e stimulus of invasive disease, which may include stimulation of T(H)2 cyto kine production.