Cells release ATP during inflammatory processes or tissue damage. In our study we investigated the interaction of the P2X7-receptor on the calcium signalling of B lymphocytes induced by B cell receptor (BCR) ligation. In B cells ligation of BCR induces a biphasic Ca²⁺ response. Activation of the P2X7 receptor raises a cationic ion current which carries sodium, calcium and potassium. The extent of the accompanying increase in the global intracellular calcium concentration is dependent on the degree of the depolarisation of the cell membrane, which in turn is dependent on the activation and expression level of the P2X7 receptor. B lymphocytes were isolated from human from tonsils and purified by means of the nylon wool method. The cells were loaded with Ca²⁺-sensitive and membrane potential-sensitive dyes. The fluorescence signals were measured by flow cytometry. The cells were stimulated by the ligation of the BCR by human F(ab')2 anti-m antibodies in combination with rising concentrations of the P2X7 receptor agonist BzBzATP. We found a concentration dependent effect of BzBzATP on the BCR-Ca²⁺-response in P2X7-receptor expressing cells which was inhibiting at low concentrations (1 mM) and additive at higher concentrations (50 mM) of BzBzATP. The interaction of these two receptors might be significant for the modulation of the innate immune response.