The action of ultra-violet rays on complement

Abstract

The destructive action of ultra-violet rays on the complement of guinea-pig serum is primarily due to inactivation or destruction of the heat-labile protein components. More intensive irradiation leads to a slight loss in the relatively heat-stable components, but the rate of this inactivation is very small with undiluted serum. The relatively heat-stable components present in guinea-pig serum which has been heated at 56 C. for 30 min. are not affected to any appreciable extent by irradiation sufficient to destroy the complete complement activity of the unheated serum. Irradiation of the isolated globulin and albumin fractions of complement leads to similar conclusions, but the inactivation is much more rapid with these dilute solutions. The rate of inactivation of complement by ultra-violet rays is increased greatly by dilution of the serum with distilled water or 0.9% NaCl. Inactivation of complement by ultra-violet rays is not due to oxidative effects, but rate of inactivation in vacuo is slightly lower than in air. Irradiation of guinea pigs with ultraviolet does not increase appreciably the complement activity of the serum, nor does the serum of guinea pigs kept in the dark show any marked loss of this power.