Toxoplasma gondii: a new diagnostic approach based on the specific binding of erythrocytes to lymphoid cells.

Red blood cells coated with toxoplasma antigen were bound to surface receptors, possibly of Ig nature, on lymphoid cells which appeared in the spleen of albino rats a few days after intraperitoneal injection of living T. gondii of the RH strain. Antigen-binding cells appeared before specific antibody, then declined in number, while the antibody response was progressing.Available information stresses the identity of antigen-binding cells with precursors of antibody-forming cells, thus pointing to the early occurrence of the immunocytoadherence phenomenon in the immune response. The applicability of these concepts to the field of human toxoplasmosis was proved by the demonstration of circulating lymphocytes specifically binding toxoplasma antigen early in the course of human toxoplasmic lymphadenitis and only in relation to active disease, thus providing an interesting approach to the early diagnosis and the detection of the active state of the disease.Possible clinical implications are discussed.