In vitro production of anti-influenza virus antibody after intranasal inoculation with cold-adapted influenza virus.

We have studied the production of anti-influenza virus antibody in vitro by peripheral blood mononuclear cells (PBMC) obtained from 7 normal volunteers at various times after intranasal inoculation with cold-adapted A/Alaska/6/77 [H3N2] influenza virus. Antibody released into culture supernatants was assayed by a 2-step enzyme-linked immunosorbent assay (ELISA). Cells obtained 6 days after intranasal inoculation spontaneously released both IgG and IgA anti-influenza antibody; this antibody production occurred within 24 hr, was specific for the virus used to inoculate the volunteers, and was inhibitable by cycloheximide. When day 6 cells were cultured in vitro for 12 days with the polyclonal activator pokeweed mitogen (PWM), no increase in the amount of antibody above that released in the absence of PWM was seen. In contrast, cells obtained 27 days after inoculation made no spontaneous antibody. In addition, cultures of these day 27 cells with PWM resulted in the production of large amounts of IgG antibody but relatively little IgA anti-virus antibody. Thus, after a mucosal influenza virus infection, several subpopulations of functionally different cells sequentially appear in the peripheral circulation: an initial population of cells secreting IgG and IgA antibody spontaneously, followed by a 2nd population of cells secreting IgG antibody when stimulated with PWM.