The present invention provides novel immunotherapeutic compositions and methods useful for treating or preventing microbial infections, weakened immune systems, diseases in which cells have become obligately anerobic and cellular proliferative disorders including cancer. The immunotherapeutics herein use benzaldehyde derivatives, precursors and intermediaries alone or in combination with additional therapeutic agents to stimulate the immune system and inhibit cellular proliferation. The immunotherapeutics of the present invention are particularly useful in the treatment of microbial infections and cellular proliferative disorders which are resistant to traditional methods of treatment such as antibiotics and chemotherapy