Recognition of respiratory syncytial (RS) virus proteins by human and BALB/C CD4+ lymphocytes

Lymphocyte proliferation assays were used to determine the ability of human and BALB/c T-lymphocytes to recognise and respond to in vitro challenge with purified preparations of four respiratory syncytial (RS) virus proteins. Human peripheral blood lymphocytes (PBLs) collected from adult donors as well as primed BALB/c mouse splenocytes each responded specifically to challenge with intact RS virus and preparations of the fusion (F), attachment (G), 23 kilodalton (23K), and 34K phospho- (P) proteins of the virus. F protein was recognised most frequently by human PBLs, and elicited higher levels of response than equivalent concentrations of the other protein preparations examined. The human PBL proliferative responses elicited by in vitro challenge with intact virus antigen as well as with each of the four protein preparations were found to be confined to the CD4+ T-helper (Th) sub-population of lymphocytes. However, proliferative responses to intact virus and F protein were found to be accompanied by only modest and inconsistent production of Interleukin-2 (IL-2). Finally, no evidence was obtained to indicate that any of the challenge antigens employed in this study were intrinsically mitogenic, as neither naive human cord blood lymphocytes, nor un-primed BALB/c mouse splenocytes proliferated when challenged with intact RS virus or with F, G, 23K, or P protein preparations.