IMIDAZO[2,1-B]THIAZOLE DERIVATIVES .11. MODULATION OF THE CD2-RECEPTOR OF HUMAN-T TRYPSINIZED LYMPHOCYTES BY SEVERAL IMIDAZO[2,2,1-B]THIAZOLES

About 40 substituted imidazo[2,1-b]thiazoles were obtained in order to study their in vitro immunological effect on the modulation of the ex pression of human T trypsinized lymphocytes by the CD2 receptor. A syn thetic program was developed to introduce either an oxygenated functio n, such as ester (11, 14), acid (12) and arylketonic groups (9, 13, 15 ), or two groups, such as an aryl and an ester (1, 6, 8), an acid (3, 7) or a hydrazide (2). These compounds were examined by an E-rosette-f orming-cell test, and display a positive drug efficacity index, sugges ting a regeneration effect on the expression of CD2 receptors. The fol lowing structural parameters are favourable: an aryl moiety on the C-6 with a methoxy or nitro group; and an ethyl ester on the C-3, a doubl e bond to the 2,3-position (the 5,6-position is ineffective). Acid and hydrazide functions or the loss of phenyl group on the C-6 decrease t his activity. If the aryl group is on the C-3 or C-2 side chain, the a ctivity is weaker and more so for the latter. However, the most intere sting derivatives are less immunostimulating than levamisole hydrochlo ride.