Journal of Dermatological Science 25 (2001) 87 – 92 Normal proliferative responses of peripheral blood mononuclear cells to streptococcal preparation OK-432 in patients with pustulosis palmaris et plantaris constitute a distinct feature from the reduced responses observed in those with psoriasis vulgaris, pustular psoriasis, and acrodermatitis continua of Hallopeau Kazuhiro Takahashi a, *, Setsuya Aiba a , Zia Uddin a , Hidefumi Kasai b , Hachiro Tagami a a Department of Dermatology, Tohoku Uniersity School of Medicine, Seiryo -machi 1 -1, Aoba -ku, Sendai 980 -77, Japan b Department of Pharmacokinetics, Dainippon Pharmaceutical Co., Ltd., Enoki 33 -94, Suita, Osaka 564 -0053, Japan Received 9 February 2000; received in revised form 26 April 2000; accepted 27 April 2000 Abstract It was previously reported that peripheral blood mononulcear cells (PBMC) from the patients with psoriasis vulgaris (PV) showed a reduced proliferative response in vitro to the stimulation of a lyophilized preparation of penicillin-treated low virulence Su-strain of Streptococcus pyogenes group 3, OK-432. In this study, at first it was examined whether OK-432 acts as a superantigen. By analyzing the usage of V T-cell receptor (TCR) of proliferating T cells stimulated with OK-432, it was found that OK-432 stimulated preferentially V2 TCR-bearing T cells. Next, to find differences in in vitro responses of PBMC among various types of sterile pustular dermatoses such as pustulosis palmaris et plantaris (PPP), acrodermatitis continua of Hallopeau (AC), and generalized pustular psoriasis (GPP), the proliferative responses of PBMC obtained from these patients under the stimulation of OK-432 were compared. When the PBMC was stimulated with interleukin (IL)-2, no significant difference was found in their proliferative responses among those obtained from the patients with these sterile pustular dermatoses, PV or healthy controls. However, like those from PV patients, PBMC from AC and GPP patients showed significantly smaller responses to OK-432 than those from the healthy controls. In contrast, the proliferative responses of PBMC from the patients with PPP to OK-432 was comparable to those from healthy controls. These results, in addition to its unique clinical and histopathological characteristics, suggest that PPP has a different pathogenetic background from that underlying PV, AC, or GPP. © 2001 Elsevier Science Ireland Ltd. All rights reserved. www.elsevier.com/locate/jdermsci * Corresponding author. Tel.: +81-22-7177271; fax: +81-22-7177275. E-mail address: tak-cat@mail.cc.tohoku.ac.jp (K. Takahashi). 0923-1811/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII:S0923-1811(00)00109-2