Effect of partially purified B- and T-lymphocyte inhibitory factors on the mitogenic and chemotactic responses.

Avian lymphocyte inhibitory factor (LyIF) is produced by thymic (T) and bursal (B) lymphocytes following sensitization of chicks to Mycobacterium tuberculosis. Our previous studies showed that maximum activities for both B- and T-LyIF were within a molecular weight range of 10,000 to 50,000 daltons (LyIF-III). These results led us to question what other functional differences may exist. The chemotactic and mitogenic properties of B- and T-LyIF-III were investigated. Neither B- nor T-LyIF-III had chemotactic properties whereas both lymphokines significantly inhibited the uptake of [3H]-thymidine in the presence of phytohemagglutinin-M. Inhibition of migration by LyIF-III may be a reflection of LyIF-III inhibition of deoxyribonucleic acid synthesis.