Together with co-stimulation from the T lymphocytes (T-cells), naïve B-cells become fully activated and go on to proliferate and differentiate into memory and plasma cells, with the latter serving as the key engines for producing specific antibodies.
China is widely seen as a key engine of growth, especially as the US economy remains in the doldrums, with rising unemployment and many of its major manufacturing industries still badly hit.
The phenomenon is fairly recent, but has picked up rapidly in the past few years as Asia's appetite for industrial, consumer and luxury goods has emerged as a key engine of growth for Western companies struggling at home.
Darling rightly identified small businesses as a key engine for growth and unveiled measures to ease their tax burden and improve access to finance.
It inverts the anti-porn mistake of seeing porn as the key engine of transformation, instead giving it no power whatsoever.
The BPI is right to pinpoint streaming as a key engine of growth for the music industry, but it remains to be seen which companies have the legs to make that growth sustainable in the longer term.
Economic research has identified innovation as a key engine for economic growth, competitiveness and employment.
Over the years, the Kauffman Foundation, the world's largest foundation dedicated to the promotion of entrepreneurship, has sponsored research and programs to promote entrepreneurship as a key engine of economic prosperity in the United States and abroad.
It points to early investment in mobile as a key engine for growth, with €1 in every €3 spent via its mobile apps in Spain, while in Mexico the figure rises to more than 40% of sales — and up to 60% during holiday dates.
Aberdeenshire Council leader Jim Gifford said: "The UK and Scottish governments have identified city regions as being one of the key engines of economic growth.
