Symposium on infectious complications of neoplastic disease (Part II). Immunoprophylaxis and serotherapy of bacterial infections.

Immunologic approaches to the prevention and treatment of bacterial infections date back to the antecedent century. Recent interest and controversy has centered about the efficacy of gram-negative bacillary vaccines, antiserum against endotoxin, and pneumococcal vaccines. Immunization of cancer patients with Pseudomonas lipopolysaccharide vaccines has yielded inconsistent results. Factors limiting the further application of this approach are the poor immune responses in neutropenic patients and the marked pyrogenicity and pain associated with vaccine administration. Similarly, patients being treated for neoplasms of the hematopoietic system are not likely to show good antibody responses to pneumococcal antigens, even though they are not toxic. Pneumococcal immunization appears to be effective, at least as measured in terms of antibody titers, in those patients with lymphoma who have not undergone splenectomy and are not receiving chemotherapy at the time of immunization. The most reliable approach towards immunoprophylaxis may be the passive one, with antibody being produced in normal donors. The antibodies are short-lived, and this type of prophylaxis still needs to be evaluated in controlled trials. In a recently completed controlled therapeutic trial, the therapeutic application of an antiserum against core endotoxin antigens resulted in a significant reduction in deaths and increased recovery from shock complicating gram-negative sepsis. However, antiserum failed to protect cancer patients or neutropenic subjects.