Curious about what happens when you take instant coffee, separate it into components that have different molecular weights, and then stick those component separately into different test tubes that have rat spleen cells in them? If so, this is the study for you:
“Influence of molecular weight on in vitro immunostimulatory properties of instant coffee,” Cláudia P. Passos, Márcio R. Cepeda, Sónia S. Ferreira, Fernando M. Nunes, Dmitry V. Evtuguin, Pedro Madureira, Manuel Vilanova, and Manuel A. Coimbra, Food Chemistry, vol. 161, 2014, pp. 60-66. The authors report:
“Instant coffee was prepared and fractionated into higher (>100 kDa), medium (5–10, 10–30, 30–100 kDa) and lower (1–5, <1 kDa) molecular weight fractions…. The fractions obtained were incubated in vitro with murine spleen lymphocytes in order to evaluate their possible immunostimulatory abilities…. [The] fraction with 1–5 kDa was able to induce activation of B-lymphocytes. This was the only fraction to induce B-lymphocyte activation, since all the other fractions failed, even when higher concentrations were used.”