Combined effects of in vitro penicillin and sickle cell disease sera on normal lymphocyte functions

Previously published work has shown that sera from healthy sickle cell disease (SCD) patients inhibits normal lymphocyte response to phytohemagglutinin (PHA) in vitro. The objective of the current study is to ascertain what the combined effects of SCD sera plus penicillin have on normal lymphocyte cytokine production and mitogenic response to PHA. Steady state sera from 20 SCD patients not on penicillin prophylaxis and 20 comparable healthy controls were used in all experiments. Four normal healthy individuals were used as donors for obtaining peripheral blood mononuclear cells (PBMC), by density gradient. PBMC with or without penicillin were PHA stimulated by standard in vitro culture for mitogenic response and cytokine production. Supernatant cytokine levels for interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha and interleukin (IL)2 were quantified by ELISA technique. Results revealed suppression of mitogenic response in the SCD group with or without penicillin, compared to control sera (P < .001). Cytokine production in the SCD sera group showed increased production of IFN-gamma and TNF-alpha in the absence of penicillin, but suppression at all doses of penicillin. The control group results were as follows: no significant difference in IFN-gamma production with or without penicillin, mean TNF-alpha levels were the opposite of SCD sera with lower levels in the absence of penicillin. IL-2 production demonstrated a similar pattern for both groups of sera. IL-2 production was low without penicillin, but there was increased production with penicillin, which appeared dose related. The data suggests that sera from healthy SCD patients and in vitro added penicillin may have a combined suppressive effect on normal lymphocyte in vitro production of IFN-gamma and TNF-alpha. The current study results suggest that penicillin has the beneficial effect of decreasing TNF-alpha production and increasing IL-2 production when combined with SCD steady state sera. However, this in vitro benefit must be weighed against suppression of IFN-gamma production and ultimately, perhaps the long-term utility of penicillin prophylaxis in patients with SCD.