Chemokine receptor binding heterocyclic compounds with enhanced efficacy

A method to increase white blood cell (WBC) count by enhancing the population of progenitor and/or stem cells in a subject, which method comprises

• administering to said subject a compound of the formula
• or a pharmaceutically acceptable salt or pro-drug form thereof;
• and including any stereoisomeric forms thereof;
• wherein n4 is 2-4;
• each R1 is independently H, halo, alkyl, alkoxy, or CF3;
• each R2 is independently H or alkyl;
• R3 is H, alkyl, alkenyl, arylalkyl, or aryl;
• each R4 is independently H or alkyl, or the two R4 groups may be taken together with the ring to which they are attached to form an optionally substituted 6-membered aromatic or heteroaromatic ring;
• and
• each R6 is independently H or alkyl, acyl, arylacyl, or arylsulfonyl, wherein the aryl moieties thereof optionally contain one or more heteroatoms selected from the group consisting of O, S, and N;
• in an amount effective to increase said WBC count in said subject.