Immunomodulatory effects of tretinoin in combination with clindamycin.

BACKGROUND: Since acne is a multifactorial skin disease, therapies affecting several etiologic factors can have a higher than expected effectiveness. A combination of the antibiotic clindamycin phosphate and the retinoic acid tretinoin was developed. OBJECTIVE: Anti-inflammatory and immunomodulatory effects of tretinoin in vitro were studied on human keratinocytes and peripheral blood mononuclear cells (PBMCs). Effects of clindamycin phosphate on tretinoin effects were studied. METHODS: Anti-inflammatory effects on keratinocytes were assessed using an in vitro model with PMA (phorbol ester)-stimulated A431 cells (human epidermoid carcinoma). Immunomodulatory effects were measured on superantigen (SEB) stimulated PBMCs. RESULTS: Tretinoin showed very potent inhibition of PMA-stimulated IL-6 (interleukin 6) release by A431 cells. The addition of clindamycin phosphate did not interfere with this effect. Tretinoin very potently stimulated IL-5 release, and inhibited IFN gamma release by SEB-stimulated human PBMCs. This indicates an immunomodulatory effect, stimulating Th2, and inhibiting Th1 dominated responses. These features have been related to the healing of acne lesions. The addition of clindamycin phosphate did not interfere with the immunomodulatory effects of tretinoin. CONCLUSION: The combination of tretinoin and clindamycin phosphate can be expected to be very effective in acne therapy.

Idiotype switching of CD4-specific monoclonal antibodies can prolong the therapeutic effectiveness in spite of host anti-mouse IgG antibodies.

Immunotherapy using murine monoclonal antibodies (mAb) is limited by the host anti-mouse IgG response. Previous investigations demonstrated that a large proportion of the anti-mouse response was specific for idiotypic determinants of the mAb. This study demonstrates the feasibility of idiotype switching of therapeutic mAb to evade this anti-idiotype response. In this way prolongation of the therapeutic effectiveness of mAb treatment can be achieved. Using different CD4-specific mAb consecutively in rhesus monkeys it was possible to obtain therapeutic effectiveness in spite of host anti-mouse IgG antibodies, provided that no anti-idiotypic antibodies were present. Anti-constant part antibodies may even enhance therapeutic effectiveness.

Characterization of the SS-B (La) antigen in adenovirus-infected and uninfected HeLa cells.

The molecular composition and subcellular localization of the antigens recognized by anti-SS-B (La or Ha) antibodies was investigated. Ten anti-SS-B sera were selected by indirect immunofluorescence and by their immunological identity in counter-immunoelectrophoresis (CIE) with an anti-SS-B reference serum. All sera precipitated virus-associated (VA) RNA from cellular extracts of adenovirus-infected HeLa cells. Earlier results had shown that in adenovirus-infected HeLa cells a cellular 50 000 mol. wt. protein was tightly associated with VA RNA in situ. Our present results indicate that this 50 000 protein is the only SS-B antigen present in adenovirus-infected as well as in uninfected cells. A major part (greater than 80%) of the SS-B antigen is present in a readily extractable, soluble form. The rest is found in an insoluble form tightly associated with an internal nuclear structure that is mostly referred to as the nuclear matrix. Both forms are very susceptible to proteolytic degradation resulting in at least two distinct breakdown products of mol. wts. 40 000 and 25 000. The cellular 50 000 polypeptide is present in extracts of various types of cells and tissues, indicating that this antigen is very well conserved during evolution. The association of the 50 000 mol. wt. antigen with host- as well as viral-coded RNA polymerase III products also suggests an important function for this protein in the metabolism of these small RNAs.