Differential phagocytosis of CD64hi and CD64lo mcrophages after stimulation with luminal content and immune complexes

Tucumas

Congreso; LXVII Reunión Científica Annual de la Sociedad Argentina de Inmunología.; 2019

Sociedad Argentina de Inmunología

-Previously we have shown that bacteria isolated from feces of control C57BL6 or sodium dextran sulfate-induced colitis (DSS) mice exhibit a different pattern of opsonization with IgG and IgA antibodies. We wonder if differences could be due to changes in the luminal content (LC) in an inflammatory environment. To answer this question colonic LC was collected from control or DSS treated mice (day 7), filtered and tested in two trials: 1- Sorted F4/80+ macrophages (MØ) of control or DSS mice were stimulated 60 min-37°C with pH-sensitive green conjugated bacteria (pHg bacteria) previously incubated with control or DSS LC. 2- A suspension of E. coli ATCC (#) was incubated 30 min-37 C with control or DSS LC and then stained with anti-IgA and anti-IgG. 1-After stimulation with pHg bacteria incubated with control or DSS LC F4/80+ MØs split into CD64hi and CD64low subgroups (70% versus 30% respectively) regardless of their origin. CD64hi MØs showed the highest phagocytic capacity (p<0.05) while CD64low cells only engulfed pHg bacteria incubated with DSS LC. 2- The E. coli ATCC incubated with DSS LC exhibited the same pattern of opsonization of the IgG and IgA immunoglobulins previously observed with fecal bacteria with a higher frequency of IgG + IgA + bacteria (75% vs. 44%) than those treated with control LC. We describe here the strong opsonizating activity of DSS LC.The ability to stimulate CD64low MØs resident in the lamina propria could expands the spectrum of cells with proinflammatory potential